Here we have a number of simple tips and practice at adding three 2-digit numbers mentally.
By Year 6 children should have a wide range of techniques at their fingertips for adding mentally.
Some of the tips on this page include:
starting with the largest digit
adding the tens before the units
looking for pairs that make 10
add the nearest whole ten and adjust (eg add 39 by adding 40 and subtracting 1)
How to add three 2-digit numbers