Question

6.43×78.6+7.86×17.4+8.17×21.4的简便方法？

Answer 1

前二项提公因子7.86
6.43*78.6+7.86*17.4+8.17*21.4
=64.3*7.86+7.86*17.4+8.17*21.4
=7.86*（64.3+17.4）+8.17*21.4
=7.86*81.7+8.17*21.4
=7.86*81.7+81.7*2.14
=81.7*（7.86+2.14）
=81.7*10
=817

Answer 2

6.43×78.6+7.86×17.4+8.17×21.4
=78.6x（6.43+1.74）+8.17x21.4
=8.17x（78.6+21.4）
=8.17x100
=817

Answer 3

6.43×78.6+7.86×17.4+8.17×21.4
=6.43×78.6+78.6×1.74+8.17×21.4

=78.6×（6.43+1.74）+8.17×21.4
=78.6×8.17+8.17×21.4
=8.17×（78.6+21.4）
=8.17×100
=817