Question

(c) The largest 2-digit multiple and the smallest 3-digit multiple of 19:​

Answer 1

Answer:

Hmmmm. What is the largest 3-digit (decimal) number? Answer: 99 .

Now, is 99 divisible by three?

Let’s use the old “sum-of-the-digits” trick and add up the two digits: 9 + 9 = 18 .

Well, that trick is recursive, so let’s do it again: 1 + 8 = 9 .

Since the sum of the digits is a multiple of 3, then the number is divisible by 3

(It’s also divisible by 9, because the sum of its digits is divisible by 9; but that was not the question.)