OPERATIONS

Missing Number Calculations

Learn the reliable method for missing number calculations, then apply it to 11+ exam-style questions.

1 · WHAT YOU NEED TO KNOW

The idea

A missing number is found from the relationship between the known values.

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

Follow these steps

  1. Represent the blank as an unknown.
  2. Use the inverse operation to isolate it.
  3. Substitute the result into the original calculation.
3 · WORKED EXAMPLES

See the method in action

Example 1

Complete the calculation: □ + 21 = 59.

  1. Use the inverse operation: 59 - 21 = 38.
Answer: 38
Example 2

A number is multiplied by 5, then 11 is added, giving 176. What was the number?

  1. Undo the addition: 176 − 11 = 165.
  2. Then divide: 165 ÷ 5 = 33.
Answer: 33
4 · ELEVENSPRINT TIP

A useful shortcut

Substitute the result into the original calculation.

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.