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计算 能简便计算的要简便计算.(1)130+142+156+172+190(2)1998÷1

2022-08-14 02:54:19 问答库 阅读 200 次

问题详情

计算,能简便计算的要简便计算.
(1)1

30

+1

42

+1

56

+1

72

+1

90

(2)1998÷19981998

1999

(3)(9+92+93)×0.01(4)13.5×[1.5×(1.07+1.93)]

(5)1

12

+11

12

×(5

2

-1

3

)(6)(333+667)÷[63×(4

7

-4

9

)].

参考答案

(1)130+142+156+172+190
=(15-16)+(16-17)+(17-18)+(18-19)+(19-110)
=15-110
=110

(2)1998÷199819981999
=1998÷1998×1999+19981999
=1998×19991998×2000
=19992000

(3)(9+92+93)×0.01
=[9+9×(9+9×9)]×0.01,
=[9+9×(9+81)]×0.01,
=[9+9×90]×0.01,
=[9+810]×0.01,
=819×0.01,
=8.19

(4)13.5×[1.5×(1.07+1.93)]
=13.5×[1.5×3]
=13.5×4.5
=60.75

(5)112+1112×(52-13)
=112+1112×136
=112+14372
=14972

(6))(333+667)÷[63×(47-49)]
=1000÷[63×47-63×49]
=1000÷[36-28]
=1000÷8
=125

考点: