3/15 - 3/10 =? Understand Fractions? Let’s test your basic math skills!
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- Опубликовано: 9 сен 2024
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In this case the hard way is as fast as seeking a shotcut. LCD is 30
6/30 - 9/30 = -3/30 = -1/10
@@davidmata9952"easier" is subjective and personal. There's no objective reason why calculating this in terms of tenths is superior to calculating it in terms of thirtieths, or vice versa.
Personally, I found it more instinctive and natural to do the latter. YMMV.
I just 30/150 - 45/150 = -15/150 = -1/10 not hard either.
@@davidmata9952Well, I saw 30 being the LCD instantly..the numbers were small and easily doubled and tripled...so that was nearly an instantaneous thought process .
Thinking in terms of going down, then up again , seemed to involve a few more microseconds of thought processing ...for me.😜
I doubt anyone would argue the scientific notation should be involved here...which was designed to handle extremely large numbers.
@@davidmata9952 What's that got to do with anything?!
We're talking about two different approaches, both of which involve a subtraction calculation with single digit numbers. Scientific notation, and the cumbersome nature of the very large numbers it is designed to handle, doesn't come into it!
@@davidmata9952That's got nothing to do with your assertion that I'm refuting.
I did it in my head in 3 seconds way different than anybody else would.
3/15 is 1/5 - 3/10 (which is 1.5/5) = -.5/5 = -1/10
3/15 is 1/5 is 2/10 ... 2/10 - 3/10 = -1/10.
Different but equally valid
paused at 1:47. Got it right. Reduced 3/15 to 1/5; making the CD 10. Therefore 2/10-3/10. Result -1/10. Now on to the video to see how I did.
Fractions are fUN! You pointed out the problem if it had been 7/15 which is why I always go the direct route of LCD and do the reductions at the end. Nice Explanations.
Having been a kid in the 1970's, there is a lot I have forgotten. Thank you for such quality math videos. 🏆
I would have done that one in my head in 1947
@@theDemocraticway Well, your better than I am, I still use paper and pencil. 📝
I used to know so much more than I do now, but I learned it using “old math”. Lol. That way probably wouldn’t fly today.
I didn't think to reduce 3/15 to 1/5, I just simply set the LCD at 30, and multiplied the 3 with 2 to get 6/30, multiplied the 3 with 3 to get 9/30. That gave me -3/30, which reduced to -1/10. That's a clever idea, to reduce the fractions first, to get the lowest possible common denominator, making it easier to solve in your head: No calculator, no "scratch" paper!
TO FIND LCD AND GCF, use a venn diagram. Factor both numbers to their primes, put the ones they share in the 'common' area, the ones they don't share on the outsides. SHARED factors multiply to make GCF, ALL FACTORS multiply to make the LCD.
I can't make an venn here, so bear with me. 24 and 36, eg. ----
24 = 2×2×2×3
36= 2×2×3×3.
They share two 2s and one 3.
Diagram would be [2 (2,2,3) 3]
Ergo, GCF would be 2×2×3 and LCD would be 2x2x2x3x3.
BTW, the LCD × GCF. ALWAYS = the product of the 2 original numbers. And the reduced fraction is ALWAYS the outside numbers (in this case, 2 and 3)
super easy I will use negative exponents to represent fractions
-3(10 ^ -1) + 3(15 ^ -1) [ here I am saying negative three tenths plus three fifteenths]
-9(30 ^ -1) + 6(30 ^ -1) [Here I recognized the lcd is 30 and changed the fractions so they had common denominators]
30 ^ -1 * (-9 + 6)
-3 (30 ^ -1)
-1 (10 ^ -1)
Final answer is negative one tenth
d) -1/10
You can also cross-multiply: (30/150) - (45/150 ) = (-15/150) = -1/10
Anybody out there old enough to remember the "means and extremes"?.
A/B + C/D = (AD) + (BC) / BD. Works with subtracting, too.
3/4 -1/6 = (3×6) - (1×4) / (4×6). reduce.
Easy- peasy.
Well (just looking at it) 3/10 is bigger than 3/15 so the answer is going to be 'minus'
then (quickly in my head) 3/15 - 3 /10 is 6/30 - 9/30 = - 3/30 which is - 1/10
or 3/15 is 1/5 which is 2/10 giving us 2/10 - 3/10 which is - 1/10
Lengthy solutions.
Having been a scientific programmer and statistician I rewrite the expression as (3x(1/15)) - (3x(1/10)) then apply order of precedence or operations (and a calculator 😮 (😢)) arrive at -(1/10) 😃 🧮
Love doing mental maths keeps the brain going
got it -1/10 easy LCD of 30 subtract to a -3/30 reduce thanks for the fun
LCD is 10 ... 3/15 is 1/5 is 2/10 ... 2/10 - 3/10 = -1/10
I would have never became a civil engineer if you were my first math teacher.
I thought this was some sort of tricky question because of the thumbnail claiming that many will get it wrong! Turns out it was really basic. Regardless I am happy with reviewing basic math skills. It is important to keep the foundations strong
The easiest and quickest way the solve this is to multiply the left term by one in the form of 2/3 over 2/3, resulting in 2/10 - 3/10 = 1/10.BTW I got my math degree exactly fifty years ago.
I got it right!
While you were learning math in 1977 I was in college and soon after in the military however, I always enjoyed math and that is why I love your channel. Every time one of your videos pops up I have a need to test myself. For the record, I usually have the right answer. I knew Aunt Sally too.
I always equate math with money or food. LOL Fractions are pizzas and +/- numbers are a check book. My mother had an issue with negative numbers until I asked her to bring her check book over and I asked her you have $750 in your checking account and you write a check for $800 what do you do? Her response was priceless. She said I have to run like hell to the bank and deposit at least $50. Yep, that is your negative number.
Solved in my head at the thumbnail, my answer is d) -1/10.
0) 3/15 - 3/10 -- Start
1) 30/150 - 45/159 -- cross-multiply to get a common denominator
2) -15/150 -- Subtrract the numerators
3) -1/10 -- Simplify the fraction
Greetings. The answer is negative 1/10.
(6-9)/30=-3/30=-1/10.
(30-45)/150
-15/150
-1/10
30 is the lowest common denominator. 6/30-9/30=-3/30 simplified -1/10
@@edwellmusonda6819 10 is the LCD. 3/15 is 1/5 is 2/10 ... 2/10 - 3/10 = -1/10
@@MrSummitville I'm talking without first simplifying
@@edwellmusonda681930 is the lowest common multiple of 10 and 15. That's not necessarily the same as the lowest common denominator for fractions over 10 and over 15.
Personally I tend not to worry about LCD with fraction calculations like this. I just work with an obvious common multiple of the denominators (don't care whether it's the lowest common multiple or not) and then simplify at the end.
In this case, putting everything over 30 was the natural approach for me too.
d) 30 - 45, all over 150 =. - 1/10
Alternate--
(3/15) - (3/10)
(1/5) - (3/10)
(2/10) - (3/10)
-(1/10)
Fifth grade math.
Very, very, very easy
I solved this one in my head while swimming under water across my pool.
MANY WILL GET WRONG!
An unwise sentence said by a Teacher. Many are also clever!
d) -1/10
3 3
--- - -----
15 10
3 3
----- - -----
3*5 2*5
1 3
--- - ------
5 2*5
2 - 3
--------------
2*5
-1
---
10
-10^-1
1/2
D -1/10
D) -1/10
d, don’t know how I did it
LCD = 30
LCM is 30. LCD is 10.
But it doesn't matter. All you need is any valid common denominator, then you can simplify at the end.
D.) -1/10
_१/१०
B
d.
D
👍
-1/10. How about a cash award instead of happy faces and gold stars. How about $100.00…BAAAAWAAAAAHAHAHAAAAA! Just kidding.
d
-1/10...
3/15 = 2/10
2/10 - 3/10 = -1/10
Ans.-1/10
Answer is -1/10
Informative, yes. Get to the point man! Too many tangents
_1/10
D 1/10
More confused after watching than before watching
-1/10
Typical public teacher. Just get to the point.
-⅒ in about five seconds in my head. Sorry it took so long. I'm really tired.
d) -1/10
D) -1/10
D
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d) -1/10
d) - 1/10
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A
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b
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