How do you find the twenty-fourth positive multiple of 7?

The full question states: Find the twenty-fourth positive multiple of 7 and the sum of the first twenty-four positive multiples of 7.
I know how to find the sum of the first 24 positive multiples of 7 since its similar to this but how do I find the twenty-fourth positive multiple of 7?

1 Answer
Jul 15, 2018

S=2100

Explanation:

Remember what the multiples are:

The 1st multiple of 7 is 1xx7 =7
The 2nd multiple of 7 is 2xx7 =14
The 3rd multiple of 7 is 3xx7 =21

The 10th multiple of 7 is 10xx7 =70 and so on.

The 24th multiple of 7 is 24xx7 =168

The sum of the first 24 multiples will be:

S= 24/2(2(7)+23(7))

S=2100

or using T_24 =168

S = 24/2(7+168)

S=2100