Question

计算(能简便的要简便)？

Answer 1

①2.5x8.19x0.4
＝(0.25x4)x8.19
=1x8.19
=8.19
②4.86x6.32-6.32x4.35
=6.32x(4.86-4.35)
=6.32x0.51
=6.32x0.5+0.01x6.32
=3.16+0.0632
=3.2232
③64x0.25x0.5x1.25
=(64÷4)÷2x1.25
=16÷2x1.25
=8x1.25
=10
④97x8.5

=776+97÷2
=776+48.5
=824+0.5
=824.5

Answer 2

2.5×8.19×0.4＝2.5×0.4×8.19
＝ 1×8.19
＝8.19
4.86×6.32－6.32×4.35
＝6.32×（4.86－4.35）
＝6.32×0.51
＝6.32×0.5＋6.32×0.01
＝3.16＋0.632
＝3.792
64×0.25×0.5×1.25
＝8×2×4×0.25×0.5×1.25
＝8×1.25×（0.25×4）×（0.5×2）
＝10×1×1
＝10
97×8.5＝（100－3）×8.5
＝100×8.5－3×8.5
＝850－25.5
＝824.5