Question

How many numbers multiple of 3 are in the range [2,2000]?

Answer 1

There are 666 numbers multiple of 3 in the interval.

Explanation:

Multiples of 3:

A number is a multiple of 3 if the sum of it's digits is a multiple of 3.

Range [2,2000]:

First multiple of 3 in the interval: 3

Last: 1998

How many:

`1 + (1998 - 3)/(3) = 1 + 665 = 666`

There are 666 numbers multiple of 3 in the interval.