First 8 multiples of 3
3, 6, 9,'12, 15,18, 21, 24
S = 3 + 6 + 9 + 12 + 15 + 18 + 21 + 24
These numbers are in A.P
where a = 3, d = 3 and n = 8
s n = n / 2 [2a + (n - 1)d]
s 8 = 8 / 2 [2 x 3 + (8 - 1)3]
s 8 = 4[6 + 21]
s 8 = 4 x 27 = 108
.'. Thus, sum of first 8 multiples of 3 of 108.
