Question

1*2*3加2*3*4加3*4*5加4*5*6加5*6*7加6*7*8加7*8*9加8*9*10 如何用小学奥数方法简算

Answer 1

1×2×3 + 2×3×4 + 3×4×5 + . + n(n+1)(n+2) = 1/4 × n(n+1)(n+2)(n+3)

所以：

1×2×3 + 2×3×4 + 3×4×5 + . + 8×9×10

= 1/4 × 8 × 9 × 10× 11

= 1980