Question

Toby picks a 4-digit number.

It is larger than 7999 and it is a multiple of 5.
How many different numbers could he have picked?

Answer 1

Total different numbers = 400

Explanation:

Assume;

Smallest number bigger than 7999( multiple of 5) = 8,000

largest 4 digit number multiple of 5) = 9,995

Computation:

a = 8,000

d = 5

an = 9,995

an = a + (n-1)d

9,995 = 8,000 + (n-1)5

1,995 = (n-1)5

399 = n-1

n = 400

Total different numbers = 400