求教数学题,要巧算25x125x48=?89x99+89=?

问题描述:

求教数学题,要巧算
25x125x48=?
89x99+89=?

25x125x48
=25x125x(6x8)
=(25x6)x(125x8)
=150x1000
=150000
89x99x89
=89x99x89x1
=89x(99+1)
=89x100
=8900

25x125x48=(25x2x3)x(125x8)=150x1000=150000

89x99+89=89x99+89x1=89x(99+1)=8900

1. 25x125x48=5²x5³x2²x2²x3=(5x2)x(5x2)x(5x2)x(5x2)x(5x3)=15x10000=150000
2. 89x99+89=89x(99+1)=89x100=8900

25x125x48=?

=25*4*125*(8+4)

=100*1000*500

=50000000
89x99+89=?

=89(99+1)

=89*100

=8900

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25x125x48
=25×(25×5)×(4×4×3)
=(25×4)×(25×4)×(5×3)-----------------乘法交换律,结合律
=100×100×15
=150000
89x99+89
=89×(99+1)--------------------------乘法分配率逆用
=8900