五年级下册的简便运算

如题所述

1:(36963-369.63)除以(24642-246.42) =369.63×(100-1)÷[246.42×(100-1)] =369.63×99÷[246.42×99]=369.63÷246.42=1.52:1999分之1+1999分之2+1999分之3+……+1999分之1998 =1999分之1×(1+2+3+4+……+1998)=1999分之1×(1+1998)×1998÷2=1999分之1×1999×999=9993:(1+1.8)+(2+1.8乘2)+(3+1.8乘3)+……+(100+1.8乘100)=(1+1.8)+2×(1+1.8)+3×(1+1.8)+……+100×(1+1.8) =2.8+2,8×2+2,8×3+……+2,8×100=2.8×(1+2+3+……+100)=2.8×(1+100)×100÷2=14140
4:(2.17+5.49+3.81)乘(5.49+2.17+9.2)-(3.81+2.17+5.49+9.2)乘(2.17+5.49)=(2.17+5.49+3.81)×(5.49+2.17+9.2)-(3.81+2.17+5.49)×(2.17+5.49)-9.2×(2.17+5.49)=(2.17+5.49+3.81)×[(5.49+2.17+9.2)-(2.17+5.49)]-9.2×(2.17+5.49)=(2.17+5.49+3.81)× 9.2-9.2×(2.17+5.49)=9.2×[(2.17+5.49+3.81)-(2.17+5.49)]=9.2×3.81=35.052
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