tidy numbers

In Tui class we have been learning how to use tidy number.tidy number are big equation like 56-  =95 but you can solve them by using a number line or by jumping. tidy numbers look really hard but it helps if you use a number line or jumping and there is other ways to solve it, here's a problem 51-  =18 and i solve this by using a number line but i could use jumping to 50 and this in the middle is 33 so 51-33=18.