Question

运用运算律可以一些计算简便为什么说一些呢？请举例说明。

运用运算律可以一些计算简便为什么说一些呢？请举例说明。

Answer 1

34×3.535-3.5×34.34
=34×3.5×1.01-3.5×34×1.01
=0
8+89+899+8999+89999
=9+90+900+9000+90000-5
=99999-5
=99994
0.67×2.1+0.018×21+8.5×0.79
=0.67×2.1+0.18×2.1+8.5×0.79
=(0.67+0.18)×2.1+8.5×0.79
=0.85×2.1+0.85×7.9
=0.85×(2.1+7.9)
=0.85×10
=8.5
22222.2×9.99999
=22222.2×(10-0.00001)
=222222-0.222222
=222221.777778
1997×19961996-1996×19971997
=1997×1996×10001-1996×1997×10001
=0
0.02+0.04+0.06+0.08+……+19.94+19.96+19.98
=(0.02+19.98)×999÷2
=10×999
=9990
99999×77778+33333×66666
=99999×77778+99999×22222
=99999×(77778+22222)
=99999×100000
=9999900000

(4又5/6-3又3/4)/(3/14+2/7)
=13/12÷1/2
=13/6
=2又1/6
(4.8/1又4/5+3又1/2+7又1/3)*4/9
=(2又2/3+7又1/3+3.5)*4/9
=(10+3.5)*4/9
=13.5*4/9
=6
17.2/【(3又2/5-1.25)*2/3】
=17.2/【2.15*2/3】
=17.2÷43/3
=1.2
5*5又1/5
=5*5+5*1/5
=25+1
=26
(5又2/5-1.8)/[(1.15+13/20)*1又2/3]
=3.6/[1.8*5/3]
=3.6/3
=1.2
3又5/8*5又1/5+5又1/5*6又3/8
=5.2*(3又5/8+6又3/8)
=5.2*10
=52
[3/4-7/8/(5/6+4/5)]*28
=[3/4-7/8÷49/30]*28
=[3/4-15/28]*28
=3/4*28-15/28*28
=21-15
=6
(1.25*4/5-0.76)/(1又3/8+1又1/40)
=(1-0.76)/2.4
=0.24/2.4
=0.1
[(0.2+1/3)*4.5]/(8又1/20-6.45)
=8/15*4.5/1.6
=2.4/1.6
=1.5