计算题,用简便方法计算.

题目

计算题,用简便方法计算.
如下：1、7.74×(2.8-1.3)+1.5×2.262、7.2×0.2+2.4×1.43、2.22×9.9+6.66×6.74、12.7×9.9+1.27

答案

1、7.74×(2.8-1.3)+1.5×2.26
=7.74×1.5+1.5×2.26
=(7.74+2.26)×1.5
=10×1.5
=15
2、7.2×0.2+2.4×1.4
=2.4×3×0.2+2.4×1.4
=2.4×0.6+2.4×1.4
=2.4×(0.6+1.4)
=2.4×2
=4.8
3、2.22×9.9+6.66×6.7
=2.22×3×3.3+6.66×6.7
=6.66×3.6+6.66×6.7
=6.66×(3.3+6.7)
=6.66×10
=66.6
4、12.7×9.9+1.27
=1.27×(99+1)
=1.27×100
=127