Question

简便计算 9.9x8.6+0.86 7.5x27/4+2.5x27/4+10x13/4 99

简便计算

9.9x8.6+0.86

7.5x27/4+2.5x27/4+10x13/4

9999+9999²

1064÷28＋1736÷28

1＋2＋3＋……＋2008＋2009＋2010

2/3×3/4×4/5×5/6×……×98/99

123＋234＋345＋456＋567＋678＋789

359÷27.3×1.254÷÷718×273÷725.4

Answer 1

9.9x8.6+0.86
=9.9×8.6+8.6×0.1
=(9.9+0.1)×8.6
=10×8.6
=86
7.5x27/4+2.5x27/4+10x13/4
=(7.5+2.5)×27/4+10×13/4
=10×27/4+10×13/4
=10×(27/4+13/4)
=10×10
=100
9999+9999²
=9999+9999×9999
=(9999+1)×9999
=10000×9999
=99990000
1064÷28＋1736÷28
=(1064+1736)÷28
=2800÷28
=100
1＋2＋3＋……＋2008＋2009＋2010
=(1+2010)×(2010÷2)
=2011×1005
=2011×(1000+5)
=2011000+10055
=2021055
2/3×3/4×4/5×5/6×……×98/99

123＋234＋345＋456＋567＋678＋789
=(123+789)×3+456
=912×3+456
=2736+456
=3192
359÷27.3×7.254÷718×273÷725.4
=(359÷718)÷(27.3÷273)×(7.254÷725.4)
=1/2÷0.1×0.01
=0.05