OPERATIONS

Mental Addition

Learn the reliable method for mental addition, then apply it to 11+ exam-style questions.

1 · WHAT YOU NEED TO KNOW

The idea

Efficient mental addition uses partitioning, compensation and number bonds.

Picture itLine up the operation one step at a time
2 · THE METHOD

Follow these steps

  1. Choose a nearby friendly number or split by place value.
  2. Complete the easier addition.
  3. Adjust for any compensation and estimate-check the total.
3 · WORKED EXAMPLES

See the method in action

Example 1

Calculate 412 + 221 mentally by compensating.

  1. Add 224, then subtract 3: 412 + 224 - 3 = 633.
Answer: 633
Example 2

A balance starts at £390. Deposits of £280 and £110 are made, then £50 is withdrawn. What is the final balance?

  1. Add both deposits to the starting balance: 390 + 280 + 110 = 780.
  2. Then subtract £50, leaving £730.
Answer: £730
4 · ELEVENSPRINT TIP

A useful shortcut

Adjust for any compensation and estimate-check the total.

5 · COMMON MISTAKES

Watch out for these

6 · TRY IT YOURSELF

Three fresh questions

Ready to check the method? You will get three fresh, validated questions.