Reviewing are different strategies

Yesterday me and my maths group got given some math questions and we had to solve. The first 4 questions we had to answer using P.V.P(place value partitioning)strategy.

The next 4 questions we had to solve using RandC (rounding and compensating)strategy.

And the the last 2 questions we had to solve using reversibility.

And that are only some of the-strategies that I have been reviewing that can also help you with your maths bye bye for now.