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:** 6

**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: