Find the missing number
Three groups of numbers each have a number in brackets made from the two outside it. Find the rule from the first two groups and use it on the third.
What the question looks like
3 (12) 4 5 (15) 3 6 ( ? ) 2
How Thena would solve it
What do 3 and 4 do to make 12? Adding gives 7, but multiplying gives 12.
3 + 4 = 7 3 × 4 = 12
Check the rule on the second group: 5 × 3 = 15. It works for both.
5 × 3 = 15
Use it on the last group.
6 × 2 = 12
Answer: 12
The usual mistakes
Checking the first group only
A rule must work for both groups before you use it.
Only trying adding
Try times, take away and dividing too, and two steps such as add then double.
Swapping the numbers round
Keep the order: the first number, then the second.
Try ten
Ten find the missing number questions
A new set every time, marked when you finish.
Have paper and a pencil ready for working out.
Questions parents ask
How do you answer Find the missing number questions?
Find a rule that makes the middle number from the outer two in the first group, then check it on the second. Only use a rule that works for both, and keep the numbers in order.
More in number puzzles
- Number seriesThe next number, from the jumps between them.
- Letters for numbersSums where letters stand for numbers.
All 21 kinds of verbal reasoning question
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