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.21 | .7266 First step, adjust the decimal point in both numbers by
sliding it two spaces to the right. In general, the outside number should not have any decimals in it, and the inside number needs to be adjusted to the same extent the outside number is adjusted.
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21 | 72.66 Next, how many times does 21 go into 72? 21....42.....63.....84...... counting upwards by 21, we see that 3 times works (63) but 4 times does not (84). Place the "3" above the one's digit in 72.
3
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21 | 72.66 Now muliply 3 by 21 (get 63) and write this under the 72 and subtract. Drop the 6 down and repeat.
3
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21 | 72.66 How many times does 21 go into 96? 21...42....63....84...105
63
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96
4 times works, but 5 times is too many. Write "4" above the tenths digit in 72.66. Also, because we need to write the decimal point in our answer directly above where it occured in 72.66.
3.4
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21 | 72.66 Multiply 4 times 21 (get 84), write this under the 96, subtract
63
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96
84
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126
Drop the last 6 and repeat. How many times does 21 go into 126?
6 times. Write this above the hundredths place in 72.66. Multiply 6 times 21 (get 126) write this under the other 126, subtract (get zero). We're done. .
3.46
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21 | 72.66
63
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96
84
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126
126
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0