Here is a number machine.
Input⟶÷2⟶+15⟶Output \text{Input} \longrightarrow \div 2 \longrightarrow + 15 \longrightarrow \text{Output} Input⟶÷2⟶+15⟶OutputFind the output when the input is 40
Find the input when the output is 25
84 exam-style questions on OCR GCSE Maths Function Machines. Each one has a worked solution and a mark scheme showing where the marks go.