Fast Mental Multiplication Trick - Multiply in your head using base 20 and 30
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- Опубликовано: 2 окт 2024
- This mental multiplication trick uses the idea of a third number - a base number - to help us multiply two numbers in your head. This series of videos first looks at multiplying numbers near 10 using base 10. The second video looks at multiplying using base 20 and 30. The third video looks at how to apply this mental multiplication trick to numbers near 50. The forth video the investigates ho to easilt mentally multiply numbers near to 100. Continue your mental math multiplication abilties here!
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My life would have been a lot different if you were my math teacher at school. Thanks a lot for your lessons!
Same here…😊
When I went to public school, they taught from a curriculum not research or experience!
They were there to get a nice pay check!😃
Yes I agree , I was terrified of my maths teacher . On a Friday afternoon double maths he’d give me homework and would say learn your times tables and on Monday morning for every you get wrong you’ll get the slipper . I hope he’s sat in hell
I am hooked, just love this stuff. I am pleased that there are so many viewers, it's good to see it's not just me then who finds this stuff exciting!
Reverend George well yes, there's over 7 billion people on earth and at least 40% have internet access. You're obviously not going to be the only one interested lol
Khonic would that be 2.8 billion people interested?????
But not all 2.8 people who have internet access are interested. Maybe even the people who *dont* have internet access are interested. You never know what goes on in people’s minds.
@@Khonic23 How many people you know that are interested in math or learning in general that go as far to look up videos on YT on math? 😂You know this generation doesnt find interest in actually using the internet to learn
Thanks my friend.
I'm nearly 60 and really enjoyed learning a new technique. Will find this very useful.
You have a patient teaching style too. Cheers
chopper hello
chopper
@@krishnavavhal7443 chopper
This technique I studied a few years ago - and many of them I have either known, been shown by colleagues, or funnily enough been shown by students of mine as they try to interpret the simplest method of doing math.
Thanks for the question!
what bse we use to multiply 3 digit numbers and how to do it??
your students are literally 90000 iq
25x22 can be done with another method which particularly I find easier though I follow your teaching and it works too.
So, to multiply any number by 25 keep in mind 25x 4= 100
That means, if we divide the other multiplicand by 4 we get this:
22÷4 ( to divide by 4 just divide by 2 twice!) Thus, 22÷2=11, now again
11÷2=5.5 X10= 550 our final answer!
But mentally you can do it in 2 seconds with practice
@@trensic5716 ong
@@abdullahmunirnouroz2090 The first step would be to find the largest multiple of 100 that is lower than both numbers.
Let's say the numbers are 254 and 337.
254 = 200+54 and 337 = 200+137 so
(200+54) * (200+137) then multiply using FOIL
= 200*200 + 200*137 + 54*200 + 54*137 then factor
= 200*(200+137+54) + 54*137
= 2*100*391 + 54*137
= 2*39100 + 54*137
= 78200 + 54*137 next use the same trick to multiply 54*137 (you might want to write down the 78200 unless you can memorize it)
so 54 = 50+4 and 137 = 50+87
(50+4) * (50*87)
= 50*50 + 50*87 + 4*50 + 4*87
hmm. I don't like 4*87, so how about this
54*137 = (54*2) * (137/2)
108*137/2 = (100+8) * (100+37) / 2
= (100*100 + 100*37 + 8*100 + 8*37) / 2
= (100*(145) + 8*37) / 2
= (14500 + 8*30 + 8*7) / 2
= (14500 + 240 + 56) / 2
= 14796 / 2
= 7000+350+45+3
= 7398
+78200 (remember?)
= 85598 Tada!
Of course 4*87 isn't really that bad so
50*(54+87) + 4*87
= 5*10*141 + 4*87
= 5*1410 + 4*87
= 7050 + 348
= 7398 same as the other way
I FEELL LIKE A MATH MASTER EHEHEHE. Spent 2 hours practicing your method. Thank you. I'm feeling more confident about my mental math now. THANK YOU. I LOVE YOU DUDE.
Your channel is amazing! After years of getting by with minimal basic math skills I decided to make some changes. Your channel is an inspiration. You make learning so much more enjoyable and natural. Now I'm getting into physics and algebra and I'm loving it! If you had told me 2 days ago that I would be multiplying double digits in my head I would have told you that you were crazy! Awesome job!
I now feel like a wizard.
RUclips just obliterated all my early years of early math education in less than 30 minutes and 2 videos. I'm buzzing in excitement as an adult.
yess also see 3blue1brown
🤯🤯🤯🤯🤯🤯🤯🤯🤯🤯
I know right! My mind is blown, and that's not easy to do!
@@no-body-nobody ???
Me too!
Same here!
he's got a nice way of speaking and a soothing voice. thanks a lot.
I'm not showing this to anyone. I really wanna beat my friend in maths and now I can. MUAHAHAHA.
Shadow 88 Me Too... MUAAAAHAHAHAHA
me too
Your friend already knows the trick . MUAHAHA.
@Jarod David They probably fat after the 2 years.
Now my day wasn't completely useless.
same ^^
Katie Morris same
same bro ^^^^^
i misread the name as Kamala Harris lol
If you smile at someone, your day will never be useless.
Love this video. I been doing the long way in my head. Now you just help me to do multiplication in my head way faster. 👍
I have never calculated in my head faster than today. I am forever changed for the better.
Best method ever. I just solved a base 200 problem this way and got it completely right the first try.
Omg! I am in love with this technique. I totally plan to use this strategy for my GMAT! Thanks again man!
Good Luck!
This is just awesome, thanks a lot for posting them. I am teaching these methods to my nephew who is 7 and he is loving them. Not to mention I LOVE them a lot. Thank you SIR
لم افهم اللغة التي تتكلم بها جيدا..... لكن شرحك كان جميل جداااااا ... فقد فهمت هذه الطريقة الرائعة 1000/100
شكرا لك .. ويسر الله لك كل عسير ......
Thank you very much x36 tec you have helped a lot of young minds in castlemaine i know that you do this to help people and this is just another comment reminding you its working, your giving people i care about a better chance. simply cant put into a chat bar how much that means to me and them
I am working towards Pilot Aptitude Test and these videos help me a lot when it comes do doing math questions without calculator.
you're literally getting me ready for my aptitude test for the navy. love your vids chief
he sounds excited when he talks its so cool
saeedie archer maths can be exciting
@@tonybarfridge4369 math is exciting
@@tonybarfridge4369 uUhuio0
Very interesting! (X+A)*(X+B)= X^2+(A+B)X+AB=((X+A)+B)*X+AB, very smart!!! Very smart way to use algebra!!
You have given me a great gift! Thank you! If only I had known this so many years ago!
Goodness gracious! I wish someone had taught me that in my school years... Still it's a good mental exercise. Thousand thanks!
I'm studying for the PCAT and needed to learn to multiply without a calculator (sadly I've become dependent on them). This video has helped A LOT. Thank you!
100% agree. Hey looking back, I hope you did well!
Same!!
same here man
Same. I take it in 2 days. Scored a 75 on my practice test but I have self confidence issues and am uneducated in simple math
Me too😊😊👍
For 26 x 35 instead of using 20 for the base number you can used 30 too. Using 30 for the base is easier. Figured it out before he used a base of 30 for the first time. 🙂 This is great!👍
Thanks for commenting - this happens in the next part video - base level 50!
Can you do a video on functions?
I would appreciate it.
You make Math seem so easy..
Thank you
Now all I need is an opportunity where multiplying 78 x 56 comes up so I can impress people.
Sadly I don't remember a time this was useful besides school.
If you don't find math useful then you are just dumb or in a dead end career
Hi 👋 I am 14 and this September I am going into year 10 and I’m always getting nervous coz I felt like I might fail math but omg I stumbled across your channel and honestly I am so grateful I have you teach me better than my teachers and I can do it at my own speed I have learnt things in less than 1 hour . I have subscribed to you , your amazing and I can’t wait to watch more videos this helps me a lot ! 😊
Wow! Just love it! Math is one of my passions.
4:42 I wouls multiply 20*28 and then subtract the extra 1*28 in my head . All numbers close to 10 20 30 or whatever can be calculated like that. But calculation always depends of the specific calculation and to the knowledge of the person trying to solve it. I was lucky to have a math teacher wit, both great skills in knowledge and great skills in getting the message through. i think most of us in class loved math. He made it so interesting, so many ways to deal with numbers. It has been a great hel pall my life, being able to calculate. We got taught a lot i newer use, like ( a+b)(a-b)= and (a+b). It was in the 70`in Denmark.
For the equation example of 26 x 35 (answered at 7:45), I decided to test my luck and try to see if I could figure it out using base 30. I was so happy when I actually got it.
Brilliant hope ill never forget this tough.
this is a really interesting metod, very usefull thanks a lot.....
Thanks for helping know my teacher will be surprised about it
you got a new subscriber here! thanks for this Sir!
With numbers such as 31x39 (same first digit and second digits that add up to 10), there is an even faster way of working it out.
Take the first digit (3 in this case) and multiply it by the number that's 1 more (4 in this case).
3x4=12.
That will give you the first 2 digits of your answer.
Then multiply the second digits (1x9=9).
This will give you the last two digits of your answer (09 in this case).
So the answer is 1209.
This is particularly useful in finding the squares of numbers ending in 5.
Take 75 squared: Multiply 7 by 8, you get 56, then multiply 5 by 5, you get 25.
Stick them together and you get 5625.
Similarly, 95 squared is 9025 (9x10=90 and 5x5=25).
Your videos are awesome. So easy to follow
Thank you very much for the tips I found this to be pretty fkn amazing and exactly what I needed for poker. You have a qld accent am I right?
Thanks for the comment!That is the accent of a Victorian who lived a lot of the time in the NT.
WA all the way
o
Thank you A LOT it was really useful god bless you hope the best for you
So much better than what the schools teach! Brilliant...
I enjoy your presentation. Thanks
Love it will take a bit of getting the brain in that mode but once done will be soo much quicker
Every since I was young iv'e had massive phobia of maths, due to my dyscalculia. Your videos were a massive help, thanks.
Hello! You do not know how much your actually helping. Thank you so much. Also, I guess this works for base 40 as well. though I haven't seen the base 50 video yet. Best wishes (;
sir you great i appreciate your hardwork
Thank you, this will help me alot since i am in grade 8. On the side I done:
19 x 26 = 494
32 x 27 = 864
43 x 37 = 1,591
52 x 38 = 1,976
64 x 71 = 4,544
106 x 98 = 10,388
43 x 51 = 2193
13 x 8 = 104
512 x 497 = 254,464
good for you
On a side note, I've* done...
On a side note, I have* done...
On a side note, I *did do these/this....
On a side note, I have also completed....(Best choice.)
Now pay attention in English class (punctuation and grammar) and you'll be good to go!
I am amazed that you did these and got them all right including some which were not covered in the video such as 106 x 98
thanks alot! now i could teach my kids about this!
Why am I doing math at 6 a.m.? I don’t use it in my career or really at all. I simply wanted to explore a math short cut and to keep my brain sharp while enduring my mid 50’s. Thanks for the brain romp, it’s fun.
Thank you for making math fun!
you are superb!! hat's off boss!!
Thank you, this helpled me so much!
Multiplying by 22 is the same as multiplying by 11 except you double the result. 27x11=2(2+7)7=297. Now to get the answer for 27x22 you just double 297. 297x2=594. Or, 27+27=54. So next you have 5(2+7)4=594.
Who’s watching in 2o19? O.O
ⱣɨnkȺđøɍȺƀłɇFøxɏ me
Hello 2020😂
So from my understanding, find the closest base number for both numbers being multiplied. Correct me if im wrong.
Example: 72 x 27 = ??, so the closest number to those two would be 40 or 50.
+Khalil Yassine i would divide that 72 by 2 and then have a nice 2*36*27 , u already know how to solve 36*27, so then u just have to multiply it by 2.
@@freakymundo Thank you! This was great help, I was having the same problem.
How would you multiply numbers that are far apart, ex like 34 × 7
For me I would just do 30x7 then 7x4 and add the answers. There’s probably an easier way tho
Your IQ is ∞×∞. Seriously, I'm considered a genius and you actually teach me things I don't know yet. You're Einstein.
this is gonna help so much in finance, thank you
Go Tigers!
Your insights and techniques regarding mental math and multiplication are greatly appreciated. This is very empowering. Thanks for sharing these concepts.
Thank you SO much, you are an amazing person. I learned so much more in TWO days of watching your videos than I did in the 4 years of high school!!! I'm definitely subscribing. Your accent makes the videos much more entertaining! Once again, thank you.
Please let me know your thoughts on the 3 step method. Thank you. Your videos are still great! Thanks a million!!!😀😀😀
I gotta say, I really love these videos ... but, especially with these "tricks", is it really quicker using this method or quicker with pen and paper?
Thank you sooooo much! I love it plus when having to be patient (like waiting in line) I like to make up numbers and do them in my head. I’m looking to get real fast at it. Thank you again!
Sir thanks you so much
This is amazing.
so helpful you need to do more of thease pleaze
I know you made this a long time ago, but I struggle with mental math and multiplication, so I completely avoided it because it made me feel so stupid. Thank you so much for helping me, these tricks are super helpful! wish I knew about you when I was younger :)
Thanks. Since I am in 4th grade this is a headstart.
This vids are great! Thank you for posting!
Showers of gratitude💜💕👍😃
thnks for the tips. really helpful.
I just wanted to thank you for posting these videos....I have never been so fast at math before!!! Thank you so much for sharing your wisdom!!!
This is amazing...Love it!!!
Thanks for helping me I am doing long multiplication in Grade four and why did you start videos?Is that explain everything?
This is great. I’ve always done something like this for easy numbers by rounding and then adding or subtracting the difference, but this is more efficient with fewer steps, and I can do it with less simple numbers.
Watching these because Im taking the medical school admissions test, which doesn’t allow calculators. Now I’m wondering why i haven’t done this years ago.
thank you so much,sir!this helps a lot...aprreciate it...love it..
Oh my G...... I love math, sad that these is not used in schools....shame on the school board. But I am teaching my grandchildren. Learning should be a gift not a struggle!
Brilliant!
It's cool, but only works where two numbers are close together. Try 14 x 89 for example... whatever base you pick, there is a lot of calculation to do after it.
This is Owesome!
He speaks with a strong mumbling accent quite hurriedly in a very soft tone. Although it's sounds phonetically pleasant , but for someone unfirmailiar it's a little difficult to follow. I am sure his intentions are quite good .
Never been so pleased to have 891 as a confirmed correct answer lol
25 x 23?
I would look at that and go 25 x 20 would be 25 x 2 add a 0 = 500. That leaves you with 25 x 3 = 75 and then 500 + 75 = 575.
for 25x anything, surely it's easier to just divide the number by 4 then x100? e.g. 25*22 => 22/4 = 5.5, *100 =550.
This is so helpful to not only myself but my middle schooler since he has been virtual schooling since March 2020. Along with your other videos you have made helping him with math so much easier. Cheers!
I cannot stop watching this series. This should definitely be taught. I couldn't imagine doing 2 digit number multiplication in my head before this yet it's so simple. Well done.
25*23 can be done this way:
25*23=25*25-50=625-50=575
this is based on the X5 * X5 trick so its not a very generalized trick but its really easy to use when its applicable
So weird. I tried to do a base 20 problem before you wrote yours and mine was 25x22! So close to yours. Anyhow, let me finish watching this. I have to train some tutors and I know this will be awesome to help them.
I prefer doing it this way:
if you have 33*27 , u have a +3 and a -3 , cz u are in base 30 , the answer will be:
(900) + ((+3 -3)*30) + (-9) . => 900 + 0 - 9 = 891
other case: If u have 25 * 22 then u have +5 and +2 => (400) + (5+2)*20) + (5*2) => 400 + (7*20) + 10 = 550
other case: if u have 32 * 27 then u have +2 and -3 => 900 + ((2-3)*30) + (-6) = 864 => 900 -30 - 6 = 864
How do i do stuff like 78× 39?!
So useful
Honestly, I'm having so much fun with this lmao instead of doing hw
I am 64 and enjoying this stuff. Thank you sir!
Unbelievable. Perfect method. Thanks. Liked, Subscribed
Hot damn.... Why hasn't YT recommended this earlier when I actually had more brain power to learn it quicker.... Thank you so much, nevertheless!
Amazing
Brilliant! I am so thankful. Finally a way to simply and quickly do math that is conceptual and leads to mental math!
Who is the inspirator of this method? Where can I read about any demonstration of it ?Thks!
thanks
31x39 = 31×40 - 31x1
31x40 = 30x40 + 1x40 = 1200 + 40
1240 - 31 = 1209