数学巧算,不要用*到整数在除小数
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数学巧算,不要用*到整数在除小数
数学巧算,不要用*到整数在除小数
数学巧算,不要用*到整数在除小数
6.2×1.01=6.2×（1+0.01）=6.2×1+6.2×0.01=6.2+0.062=6.262
2.7×16.8+16.8×8.3=16.8×（2.7+8.3）=16.8×11=16.8×10+16.8×1=168+16.8=184.8
（1.25+2.5）×0.8=1.25×0.8+2.5×0.8=1+2=3
3.01×99+3.01=3.01×（99+1）=3.01×100=301
3.01×99+99=99×(3.01+1)=99×4.01=(100-1)×4.01=401-4.01=396.99
6.3×9.9+0.63=0.63×99+0.63=0.63×(99+1)=0.63×100=63
10.8×4.2+4.2×1.2-4.2×2=4.2×(10.8+1.2-2)=4.2×10=42
1.25×(8+0.4)=1.25×8+1.25×0.4=10+0.5=10.5
3.2×0.25=0.8×(4×0.25)=0.8×1=0.8
8.4+1.6×2.5=8.4+(0.4×4×2.5)=8.4+4=12.4
1.25×8.08=1.25×(8+0.08)=1.25×8+1.25×0.08=10+0.1=10.1
2.5×84=(2.5×4)×21=10×21=210
12.5×5.6=12.5×（6-0.4）=12.5×6-12.5×0.4=75-5=70
27.6×74-27.6×16-27.6×48=27.6×(74-16-48)=27.6×10=276
9.8×7.3=(10-0.2)×7.3=10×7.3-0.2×7.3=73-1.46=71.54
6.4×(1.25+12.5)=6.4×1.25+6.4×12.5=(6×1.25+0.4×1.25)+(6×12.5+0.4×12.5)=(7.5+0.5)+(75+5)=88
18.8-8.8×0.5=18.8-4.4=14.4
34.17×999=34.17×(1000-1)=34.17×1000-34.17×1=34170-34.17=34135.83
(1.25+2.5)×8=1.25×8+2.5×8=10+20=30
2.17×9.9+0.1×2.17=2.17×(9.9+0.1)=2.17×10=21.7
0.5×1.25×2.5×64=0.5×1.25×2.5×(2×8×4)=(0.5×2)×(1.25×8)×(2.5×4)=1×10×10=100
50.9×(1.13+5.77)=50.9×6.9=50.9×(7-0.1)=50.9×7-50.9×0.1=356.3-5.09=351.21
0.25+9.6+0.75=(0.25+0.75)+9.6=1+9.6=10.6
100÷25×0.3=4×0.3=1.2
主要是用交换律和结合律计算
不要用*到整数在除小数?
