tính nhẩm :
a)9 . 24 .25
b)12 . 125 .54
c)64 . 125 . 875
d)425 .7 . 4 -170 . 60
e)8 . 9 . 4 + 6 . 7 . 12 + 19 . 4 . 18
tính nhẩm : a)9 . 24 .25 b)12 . 125 .54 c)64 . 125 . 875 d)425 .7 . 4 -170 . 60 e)8 . 9 . 4 + 6 . 7 . 12 + 19 . 4 . 18
By Serenity
`a, 9.24.25`
`=216.25`
`=5400`
`b,12.125.54`
`=1500.54`
`=81000`
`c,64.125.875`
`=8000.875`
`=7000000`
`d,425.7.4-170.60`
`=11900-10200`
`=1700`
`e,8.9.4+6.7.12+19.4.18`
`=288+504+1368`
`=2160`
` a) ` ` 9 . 24 . 25 `
` = 225 . 24 `
` = 5400 `
` b) ` ` 12 . 125 . 54 `
` = 1500 . 54 `
` = 81000 `
` c) ` ` 64 . 125 . 875 `
` = 8 . 125 . 8 . 875 `
` = 1000 . 7000 `
` = 7 000 000 `
` d) ` ` 425 . 7 . 4 – 170 . 60 `
` = 85 . 7 . 5 . 4 – 170 . 20 . 3 `
` = 595 . 20 – 510 . 20 `
` = 20.(595 – 510) `
` = 20 . 85 `
` = 2 . 10 . 85 `
` = 2 . 850 `
` = 1700 `
` e) ` ` 8 . 9 . 4 + 6 . 7 . 12 + 19 . 4 . 18 `
` = 72.4 + 126.4 + 342.4 `
` = 4.(72 + 126 + 342) `
` = 4.540 `
` = 2160 `