Question

An integer 3a5b can be divided by 5 and 6, what is the value of a + b.

Answer 1

a + b = 1 or 4

Explanation:

The integer = 3a5b

The factors of the integer includes 5 and 6

∴ 5 × 6 = 30 is a factor of the integer hence 10 is also a factor which gives b = 0

We check for factors of four digit numbers with the first digit = 3, last digit = 0, penultimate to the last digit = 5 and divisible by 30

We have a50 divisible by 30, which gives, a5 divisible by 3 which includes

15 and 45 hence a can be 1 or 4 and a + b = 1 + 0 = 1 or 4 + 0 = 4.