Jumlah bilangan kelipatan 6 antara 400 dan 500 adalah ?

a = 402

n = 402, 408, 414, 420, 426, 432, 438, 444, 450, 456, 462, 468, 474, 480, 486, 492, 498.
n = 17

b = 6

Sn = n/2 [(2×a + ((n-1)×b)]
S₁₇= 17/2 [2×402 + ((17-1)×6]
=17/2 [804 + (16×6)]
=17/2 [804 + 96]
=17/2 × 900
=15300/2
=7650

maaf kalo salah