Solving Equations with Missing Numbers for 11+ Maths
21 October 2026
Understanding missing numbers
Equations with missing numbers are common in 11+ maths. These questions ask children to find the value that makes an equation true. The unknown is often shown as a blank or a letter.
Step-by-step approach
To solve these equations, encourage your child to use inverse operations. This means doing the opposite of what is shown in the equation. If the equation adds a number, subtract it. If it multiplies, divide.
Worked example
Solve for x: 3x - 5 = 16
First, add 5 to both sides of the equation.
3x - 5 + 5 = 16 + 5
This simplifies to 3x = 21.
Next, divide both sides by 3.
3x ÷ 3 = 21 ÷ 3
This gives x = 7.
The correct answer is x = 7.
Key insight: Breaking the problem into clear steps helps children avoid mistakes and builds confidence. Encourage them to check their answer by substituting it back into the original equation.
Supporting your child
Remind your child to take their time and write each step clearly. Practising different types of missing number questions will help them feel prepared for the 11+ exam.
