Question

ii) Complete the following activity to find three digit natural numbers divisible
by 5
Three-digit natural numbers divisible by 5 are 100, 105, 110,
995​

Answer 1

Answer:

How many three-digit natural numbers are divisible by 5?

Many folks have given 180, which is the right answer but the approach taken is very lengthy, I thought.

Here’s a very simple approach.

We have to form 3 Digit Numbers that are divisible by 5 and we have to select from the digits 0 .. 9 i. e. in all 10 digits.

Now, there are 9 choices for the first digit, since we can’t have 0 as the first digit. There are 10 choices for the 2nd digit and only 2 choices (0 or 5) for the 3rd digit, as the number should be divisible by 5. These are all mutually exclusive choices and thus the answer would be given by

9 * 10 * 2 = 180.

Thus, there are 180 three-digit natural numbers that are divisible by 5