Number series
A list of numbers follows a rule, and the question asks what comes next. The rule is usually in the jumps between the numbers.
What the question looks like
3, 7, 11, 15, ( ? )
How Thena would solve it
Write the jump between each pair of numbers.
3 → 7 → 11 → 15
+4 +4 +4
The jumps are all +4, so add 4 once more.
15 + 4 = 19
If the jumps change, see how they change: +1, +2, +3 means +4 next. If nothing fits, look at every other number, as two series can take turns.
Answer: 19
The usual mistakes
Looking at two numbers only
Check the jump between every pair before you decide.
Missing a jump that grows
Write the jumps down. If they grow, the next one grows too.
Missing two series taking turns
Look at the 1st, 3rd and 5th numbers, then the 2nd, 4th and 6th.
Try ten
Ten number series 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 Number series questions?
Write the jump between each pair of numbers. If the jumps are the same, use it again; if they grow, grow it again; if nothing fits, look at every other number, as two series can take turns.
More in number puzzles
- Find the missing numberThe rule that makes the middle number.
- Letters for numbersSums where letters stand for numbers.
All 21 kinds of verbal reasoning question
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