Question

8乘(72乘25)全部用简便方法计算 0.25乘(0.4加8) 45乘(9分之2加15分之7减5分之

8乘(72乘25)全部用简便方法计算
0.25乘(0.4加8)
45乘(9分之2加15分之7减5分之1)
28.4减(8.4加9分之5)
19又16分之15乘8
16.5-3.43-2.57

Answer 1

第一题
8 X ( 72 X 25 )
= 72 X 2 X 4 X 25
= 144 X 100
= 14400

第二题
0.25 X ( 0.4 + 8 )
= 0.25 X 4 X ( 2 + 0.1)
= 1 X 2.1
= 2.1

第三题
45 X ( 2/9 + 7/15 - 1/5 )
= 45X2 /9 + 45X7 /15 - 45/5
= 5X2 + 3X7 - 9
= 10 - 9 + 21
= 22

第四题
28.4 - ( 8.4 + 5/9 )
= 28.4 - 8.4 - 5/9
= 20 - 5/9
= 19+ 4/9

第五题
( 19+ 15/16 ) X 8
= ( 20 - 1/16 ) X 8
= 20 X 8 - 8 /16
= 160 - 1/2
= 159.5

第六题
16.5 - 3.43 - 2.57
= 16.5 - ( 3.43 + 2.57 )
= 16.5 - 6
= 10.5

Answer 2

8×（72×25）
=8×25×72
=200×72
=14400
0.25×（0.4+8）
=0.25×0.4+0.25×8
=0.1+2
=2.1
45×（2/9+7/15-1/5）
=45×2/9+45×7/15-45×1/5
=10+21-9
=22
28.4-（8.4+5/9）
=28.4-8.4-5/9
=20-5/9
=19又4/9
19又15/16×8
=（20-1/16）×8
=20×8-1/16×8
=160-1/2
=159又1/2
16.5-3.43-2.57
=16.5-（3.43+2.57）
=16.5-6
=10.5

Answer 3

8×(72×25)
=2×4×25×72
=2×100×72
=2×7200
=14400

=1440
0.25×(0.4+8)
=0.25×0.4+0.25×8
=0.1+2
=2.1

45×(2/9+7/15-1/5)
=45×2/9+45×7/15-45×1/5
=10+21-9
=22

28.4 -(8.4+5/9)
=28.4-8.4-5/9
=20-5/9
=19又4/9

19又15/16 ×8
=(20 - 1/16)×8
=20×8 -1/16×8
=160 -1/2
=159又1/2

16.5-3.43-2.57
=16.5-(3.43+2.57)
=16.5-6
=10.5

Answer 4

8*72*25=8*25*72=200*72=14400
0.25*(0.4+8)=0.25*0.4+0.25*8=2.1