Reversibility

Explain why this would be a good strategy to use and give an example.

So if my number was 456-_=256  I will use reversibility

I will do 256 plus _ = 456 then I will do add 56 and which will make 300 the I will add 56 more which make 356 and then I will add 56 more which make 400 and then I will add 56 more which will make 456. and the answer is 224