Maths Topic 04 - Function machines


Function or Number Machines is a maths skill that is commonly tested in 11+ exams and UK selective tests.

Examples

Example Question 1:

54 → [÷ 9] → __

Answer:

Explanation: Apply the rule [÷ 9] so 54 ÷ 9 = 6 

Example Question 2:

36 → [÷ 3] → [+ 20] → __

Answer: 32

Explanation: Apply the two rules in the order given [÷ 3] = 12, then [+ 20] = 32

Example Question 3:

__ ← [– 9]  ← 57 

Answer: 66

Explanation: Do the inverse of the rule to find the beginning number 57 + 9 = 66

Example Question 4:

25 → [ ? ] → 7  find the rule

Answer: –18

Explanation: Find the rule by doing an inverse operation 25 – 7 = 18

Video for a two-stage number machine:

Video for how to find the rule: