Question

几道简便计算题

（1）9.81X0.1+0.5X98.1+0.049X981
=

（2）7.8÷[(9-8.98)X2.5}
=

需要简便计算 求求 大家了 要快

Answer 1

（1）9.81X0.1+0.5X98.1+0.049X981
=9.81x0.1+5x9.81+4.9x9.81（此处简算）
=9.81x(0.1+5+4.9)
=9.81x10
=98.1

（2）7.8÷[(9-8.98)X2.5}
=7.8÷(0.02x2.5)
=7.8÷0.05
=7.8x20 （此处简算÷0.05，即÷1/20，即x20）
=156

追问

在第一个等号后 的5X9.81是什么意思 是不是把0.5变成了5 把98.1变成了9.81 小数点应该王后移吧！麻烦看看

追答

对，0.5扩大10倍，98.1缩小10倍，这就是本题简算的关键。

追问

[7.1-(1.56+1.54)]÷25
=
7分之5X[(5分之2+3分之1）÷12分之11]
=
这两道呢
麻烦一下大家

追答

[7.1-(1.56+1.54)]÷25
=(7.1-3.1)÷25
=4÷25
=4/25

(5/7)X[(2/5+1/3)÷(11/12)]
=(5/7)x[(2/5+1/3)x(12/11)]
=(5/7)x(2/5)x(12/11)+(5/7)x(1/3)x(12/11)
=24/77+20/77
=44/77
=4/7

Answer 2

=9.81X0.1+0.5X9.81X10+9.81X100X0.049
=9.81X0.1+9.81X5+9.81X4.9
=9.81X(0.1+5+4.9)
=9.81X10
=98.1

=7.8÷（0.02X2.5)
=7.8÷(2x2.5x0.01)
=7.8÷(5x0.01)
=7.8÷5x100
=7.8x100÷5
=7.8x20
=18x2=156

Answer 3

（1）=98.1×0.01+0.5×98.1+0. 49×98.1 =98.1×(0.01+0.5+0.49) =98.1 (2)=7.8÷[0.02×2.5] =7.8÷0.05 =156

Answer 4

9.81X0.1+0.5X98.1+0.049X981
=9.81X0.1+9.81x5+9.81x4.9
=9.81x(0.1+5+4.9)
=9.81x10
=98.1
7.8÷[(9-8.98)X2.5}
=7.8÷(0.02x2.5)
=7.8÷0.05
=7.8÷1/20
=7.8x20
=156

Answer 5

直接用手机计算器算应该就出来了。