We should understand it that 2 + 6 and 6 + 2 both are equal i.e. 2 + 6 = 6 + 2. In both cases answer will be 8. So we can change the order of operation.

Try to add smaller number in larger number. Let us see the following examples.

Add 2 + 6 ?

2 + 6

= 2 + (1, 1, 1, 1, 1, 1) By adding six time 1 in 2 is time taking and hard for kids.

= 8

Instead of solution of adding 2 to 6, try to add 6 to 2. In other words try to add the smaller number in larger number. While calculating mentally you need to count just next two numbers ahead.

= 6 + (1, 1)

= 8

OR

Add 2 in 6. Do this step in your mind.

Add 4 + 8 ?

OR

Instead of solution of adding 4 to 8, try to add 8 to 4. In other words try to add the smaller number in larger number. While calculating mentally you need to count next four numbers ahead.