Tính nhẩm 125 . 801 . 5 Ta có : 125 x 801 x 5 = 125 x (.....+......) x 5 = (125 x ...... ) x 5 + 125 x .... x 5 = ............ + ............ =

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`125. 801. 5`

Ta có;

`125 xx 801 xx 5`

`= 125 xx (800 + 1) xx 5`

`= 125 xx 800 xx 5 + 125 xx 1 xx 5`

`= 500 000 + 625`

`= 500625`