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1.直接写出得数。
7.2×3=
12.5×0=
0.5×0.75=
16.1×0.2=
1.2×0.6=
0.68×100=
0.5×0.04=
0.08×100=
7.9×20=
2.5×4=
2.4×5=
0.4+8.7=
9-7.7=
1-0.99=
1.68÷10×100=
7.2×3=
12.5×0=
0.5×0.75=
16.1×0.2=
1.2×0.6=
0.68×100=
0.5×0.04=
0.08×100=
7.9×20=
2.5×4=
2.4×5=
0.4+8.7=
9-7.7=
1-0.99=
1.68÷10×100=
答案
1. 21.6 0 0.375 3.22 0.72 68 0.02 8 158 10 12 9.1 1.3 0.01 16.8
2. 判断,对的在括号里画“√”,错的画“×”并改正。
(1) $7.5+2.5×1.2$
$=10×1.2$
$=12$
(
改正:
(2) $8×(0.4+12.5)×5$
$=8×12.5+0.4×5$
$=100+2$
$=102$
(
改正:
(1) $7.5+2.5×1.2$
$=10×1.2$
$=12$
(
×
)改正:
(2) $8×(0.4+12.5)×5$
$=8×12.5+0.4×5$
$=100+2$
$=102$
(
×
)改正:
答案
2.(1) × 7.5+2.5×1.2=7.5+3=10.5
(2) × 8×(0.4+12.5)×5=8×5×0.4+8×5×12.5=16+500=516
(2) × 8×(0.4+12.5)×5=8×5×0.4+8×5×12.5=16+500=516
3. 递等式计算。(能简算的要简算)
0.25×9.87×4
5.81×5.6+2.19×5.6
12.56÷5÷0.2
32×12.5×2.5
0.25×9.87×4
5.81×5.6+2.19×5.6
12.56÷5÷0.2
32×12.5×2.5
答案
3. 0.25×9.87×4=(0.25×4)×9.87=1×9.87=9.87
5.81×5.6+2.19×5.6=(5.81+2.19)×5.6=8×5.6=44.8
12.56÷5÷0.2=12.56÷(5×0.2)=12.56÷1=12.56
32×12.5×2.5=(8×12.5)×(4×2.5)=100×10=1000
5.81×5.6+2.19×5.6=(5.81+2.19)×5.6=8×5.6=44.8
12.56÷5÷0.2=12.56÷(5×0.2)=12.56÷1=12.56
32×12.5×2.5=(8×12.5)×(4×2.5)=100×10=1000
