Add the values in ones column. For example, consider the math problem 15+38. When you add the numbers in the ones column, 5 and 8, you get 13. Because this value is greater than 9, you must regroup the numbers. Instead of having 13 ones, you have one 10 and three ones.
Write the number of ones in the ones column and move the regrouped 10s to the 10s column. In this example, write the 3 in the ones column and move the one to the 10s column. Write the 1 on top of the top number in the addition problem. In this example, write the 1 on top of the 1 in the number 15.
Add the numbers in the 10s column. In this example, you have 1, 1 and 3. Add these numbers together to get 5. Write this number in the 10s column to get your final solution.
1
15
+38
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53
Subtract the values in the ones column. For example, take the math problem 32-15. Using the values in the ones column, you would perform 3-5, an operation that isn't possible because 5 is greater than 3. Take one of the 10s and transform it into 10 ones. Now you can subtract the numbers in the ones column. 12 minus 5 is 7.
Write this number in the ones column.
Subtract the numbers in the 10s column. In this example, subtract 2 from 1 to get 1. Write this number in the 10s column to get your final solution.
32 equals two 10s and 12 ones
-17 equals one 10 and seven ones
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15 One 10 five ones