Look at my picture to see how its done.
Basically, you line the numbers up from the ones up.
If a number is higher than 9, you bump one digit to the next.
For example as shown, 6+6=12 so you write the 2 and add the tens digit (1) to the next column and you continue until you completely went through each digit.
Hope this helped you a bit.
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-Geekhawk
