Question

用简便方法计算下面各题。

用简便方法计算下面各题。
1.5x105 0.3X2.5x0.4

4.8X0.25 0.78X98

0.5x2.33x8 1.2X2.5+0.8X2.5

Answer 1

1.5×105=1.5×（100+5）=1.5×100+1.5×5=150+7.5=157.5
0.3×2.5×0.4=0.3×（2.5×0.4）=0.3×1=0.3
4.8×0.25=1.2×4×0.25=1.2×1=1.2
0.78×98=0.78×（100-2）=0.78×100-0.78×2=78-1.56=76.44
0.5×2.33×8=（0.5×8）×2.33=4×2.33=9.32
1.2×2.5+0.8×2.5=2.5×（1.2+0.8）=2.5×2=5

Answer 2

1.5x105=1.5x(100+5)=1.5x100+1.5x5=150+7.5=157.5
0.3x2.5x0.4=2.5x0.4x0.3=0.3
4.8x0.25=4x0.25x1.2=1.2
0.78x98=0.78x(100-2)=0.78x100-0.78x2=78-1.56=76.44
0.5x2.33x8=0.5x8x2.33=4x2.33=9.32
1.2x2.5+0.8x2.5=(1.2+0.8)x2.5=2x2.5=5

Answer 3

（1.5*100）+（1.5*5）

追答

0.4*0.25*0.3=0.3

0.4*0.25*0.3=0.03

0.5*8*2.33

Answer 4

1.5x105
=105×(1+0.5)
=105+52.5
=157.5

0.3X2.5x0.4
=0.3×1
=0.3

4.8X0.25
=1.2×4×0.25
=1.2×1
=1.2

0.78X98
=0.78×(100-2)
=78-1.56
=76.44

0.5x2.33x8
=2.33×4
=9.32

1.2X2.5+0.8X2.5
=2.5×(1.2+0.8)
=2.5×2
=5