The following is correct?
456 532 1087 + 36 ------ 2132
I will present how to make sure if this calculation is correct; that is, mentally calculate only each last figure:
6 2 7 + 6 ----- 26 + 2 is 8;
In this case where we made sure using each last figure only, we can determine the correctness in a probability percentage of 90.
Practically we can make sure if calculations are correct in our payments, for example, receipts from supermarkets.
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