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Greetings to everyone,

Lookin in an old book of the Teach Yourself Series I've found an example which I couldn't understand:

Divide $213$ by $39$

the procedure follows like this:(exactly as the book shows) \begin{equation} \;\;\;\;\;\;\;\;\;55\\ 39)2145\\ \;\;\;195\\ \;\;\;\;\;\;195\\ \;\;\;\;\;\;195\\ \;\;\;\;\;\cdots \end{equation}

$39$ divides $2145$ and the result is $55$; how the $2145$ comes from? when I did it, I've got $5.46...$ but if you take the calculator and divide $2145$ by $39$ it result in an exact division, you get the $55$. What is this method? I didn't know it, I always use decimals, of course I know it's rounding a number, but the book didn't mention it, how both methods can be related? Thank you all very much!

jgrsc
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The $1245$ is a typo for $2145$. Then we subtract $195(0)$ from $2145$ (where the $0$ is in parentheses because it is not shown) and get $195$.

Ross Millikan
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  • Thank you Ross Millikan I still dont' understand why the 2145 appears instead of just imply 213 – jgrsc Aug 20 '21 at 03:39
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    I think the $213$ is again a typo for $2145$. As you say, $39 \cdot 55=2145$ and the figure is long division of $2145$ by $39$ as I learned paper division decades ago. – Ross Millikan Aug 20 '21 at 03:42
  • Thank you again I was afraid of not knowing the basics, and tried to look if that was a forgotten method or a typo...but as Feynman said ''You are the easiest person to get fooled'' I got fooled by the book – jgrsc Aug 20 '21 at 03:47