Addition Tricks

Addition
-an operation of finding a sum of some numbers: 21 + 5 = 26. Here 21 and 5 – addends,  26 – the sum. If addends are changed by places, a sum is saved the same: 21 + 5 = 26 and 5 + 21 = 26.

Math tricks 1:
Adding by breaking apart a number
Example:
137+85
=(122+15)+85
=122+100
=222
In example here,break 137 to 122 and 15.
Math tricks 2:
Adding by overadding
Example:
247+97
=247+(100-3)
=347-3
=344
In example here,97 was add to 100 first.

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Easy way to check your answer: Estimating the answer by rounding off numbers
Example:

249 159 + 504 = 912

249 rounds off to 250,159 to 160 and 504 to 500,then add up these figures.

250 160 + 500 = 910

The amount that has been estimated is 910,so the answer should be around 910.If your answer is only 800,then you know it is wrong.