Question

1.6×23.2×49怎样简便运算

Answer 1

先把49换算成50-1
1.6×23.2×49=1.6×(50-1)×23.2
=(1.6×50-1.6×1)×23.2
=(80-1.6)×23.2
=78.4×23.2
到这步，又把23.2换算成20+3+0.2
78.4×(20+3+0.2)
=78.4×20+78.4×3+78.4×0.2
=1568+235.2+15.68
=1818.88

Answer 2

1.6×3.9×1.25
=1.25×8×0.2×3.9
=10×0.2×3.9
=2×3.9
=7.8

Answer 3

用乘法分配律、交换律简便，即
1.6×3×12.5
=0.8×2×3×12.5
=2×3×（12.5×0.8）
=6×10
=60

Answer 4

可以先用49×1.6得78.4后再×23.2得3841.6。

Answer 5

1.6ⅹ23.2Ⅹ49
=1.6ⅹ23.2ⅹ（50-1）
=1.6ⅹ23.2ⅹ50-1.6ⅹ23.2ⅹ1
=1.6ⅹ23.2ⅹ50-1.6ⅹ23.2
=2ⅹ0.8ⅹ23.2ⅹ50-1.6ⅹ32
=0.8ⅹ23.2ⅹ（2ⅹ50）-1.6ⅹ23.2
=0.8ⅹ23.2ⅹ100-1.6ⅹ23.2
=（0.8ⅹ100-1.6）ⅹ23.2
=（80ⅹ1.6）ⅹ23.2
=78.4ⅹ23.2
=1818.88