posted by zeke

Let's use this addition problem as an example.

21
35
___

If you have a column of numbers and you go down each column to add them together, that's normal, right?

36
95
15
146

To check to make sure you're right, you'd add from the bottom to the top of each column. If you get the same answer, you know it's right.

15
95
36
146

When my mother was working for her father in the family business (long before calculators or computers) and had to add long columns of numbers, adding down was the standard; then adding up was the double-check.

=)

thank you.

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