Now that your darling has got a solid grasp of some of the basic concepts of maths and knows about place values of numbers, he would be moving some of the things from written form to mental form. His brain now has the capability to preserve two digit numbers, form a mental picture of it and then use another 2 digit number to do some simple mathematical operations. Many games and activities that he is involved in will also be using the concept of mental maths and this will help develop that skill in your child better.
What you need to know
Number sense becomes increasingly more advanced at this age as kids start being confident about using mental maths. There are many books and concepts that can help your child develop his mental math skills. These concepts will not only help your child fare better in mathematics but will also help in his overall brain development.