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

0 bình luận về “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”

1. `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`

    

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2. ` 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 `

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