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Addition

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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.


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.

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