用简便方法和递等式计算:(1)2005×18-200.5×90+20050×0.1(2)(0.75×2.6×2.7)÷(
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(1)2005×18-200.5×90+20050×0.1

=2005×18-2005×9+2005

=2005×(18-9+1)

=2005×10

=20050

(2)(0.75×2.6×2.7)÷(0.13×0.25×9)

=(0.75×0.25)×(2.6×0.13)×(2.7÷9)

=3×20×0.3

=18

(3)(2+3.15+5.87)×(3.15+5.87+7.32)-(2+3.15+5.87+7.32)×(3.15+5.87)

=2×(3.14+5.87+7.32)+(3.15+5.87)×(3.15+5.87+7.32)-2×(3.15+5.87)-(3.15+5.87+7.32)×(3.15+5.87)

=2×(3.15+5.87+7.32)-2×(3.15+5.87)

=2×7.32

=14.64