# Number Bonds, Mental Calculation

**This time we offer a Mental and Oral maths activity which focusses on using a specific strategy to give addition a speed boost.**

This teaching activity enables children to gain confidence in reordering the numbers of an addition problem to make that problem easier. The focus is on looking for pairs which create a specific total.

You show an addition problem like this one:

**30 + 10 + 70 + 40 + 90** **Read more »**

**This Mental and Oral activity revolves around number bonds (or complements) to 100**.

Children work in pairs, using a mini-whiteboard. Ask them to draw a three by three grid and to quickly fill the grid with different multiples of 5. When they have completed this the teacher starts to call out random multiples of 5, children can circle a number on their grid if it is the other half of the pair totalling exactly 100 (the complement to 100). **Read more »**