Similar to SMO Junior 2021, Problem 10, Find remainder of 85 digit integer when divided by 6

The first 47 natural numbers are concatenated from left to right to form an integer N. Determine the remainder of N when divided by 6.
An excellent math video produced at Maths Hub Enrichment Center in Singapore stated odd multiples of 3 leave a remainder of 3 when divided by 6. This result was proven as a Lemma to finish the problem
Spainard Hikaru Aikawa questioned the validity of concatenation at Reddit.
GMAT Club worked similar problem regarding even multiples May 2004. Thanks Sarkari Naukri for his clear modular arithmetic explanations.