Adding using tidy numbers with problems,

We are learning to solve addition problems by first adding a tidy number and then subtracting a small number to compensate

Today at school my maths class room 12 and I started a new math that we could start with. It was a very hard for some of us but then we all got used to it because of our teacher. If some person asks me how to do his answer I would say your answer is 34 + 78 = 112 because 34 + 80 =114 - 2 = 112