Question

1×2+2×3+3×4＋4×5＋5×6+6×7＋7×8＋8×9＋9×10＝

要有过程，如果好的话，加15财富值
要简算，不能直接算

Answer 1

一个公式:1/3*n*(n+1)*(n+2)[n指倒数第二个数] 原式=1/3*9*10*11=330

Answer 2

1×2+2×3+3×4＋4×5＋5×6+6×7＋7×8＋8×9＋9×10
=2×4+3×4＋4×5＋5×6+6×7＋7×8＋8×9＋9×10
=4×5＋4×5＋5×6+6×7＋7×8＋8×9＋9×10
=5×8＋5×6+6×7＋7×8＋8×9＋9×10
=5×8＋5×6+6×7＋7×8＋8×9＋9×10
=5×14+6×7＋7×8＋8×9＋9×10
=10×7+6×7＋7×8＋8×9＋9×10
=7×16＋7×8＋8×9＋9×10
=21×8＋8×9＋9×10
=8×30＋9×10
=330

Answer 3

2+6+12+20+30+42+56+72+90=400

Answer 4

330

Answer 5

330