Question

(a) 117 +9 = 117+10 -1 = 127-1 = 126
(b) 117-9 = 117-10 +1 = 107 +1 = 108
please explain me​

Answer 1

Answer:

Bro doing all this will take more time in this they are breaking 9 in terms of 10 for example

+ 9 = 10 - 1

-9 = -10 + 1

This is time wasting insted increase your calculation speed but if you like this method you can go with it

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