Question

Find the sum of the first 30 positive integers divisible by 6.​

Answer 1

The number series 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, .. ..., 180.

First term (a) = 6

Common difference (d)= 6

Number of terms (n) = 30

Last term (l) = 180

$= n \div 2 \times a + l \\ = 30 \div 2 \times 6 + 180 \\ = 30 \times 186 \div 2 \\ = 5580 \div 2 \\ = 270$