CAT4 number series

Worked example

The same question, one step at a time.

1. 1Write the gap between each pair down before deciding anything: 7 to 14 is +7, 14 to 21 is +7, 21 to 28 is +7, 28 to 35 is +7.
2. 2Every gap is the same, +7, so the series adds 7 each time and nothing else is going on.
3. 3The question asks for the very next number, one gap on from 35 — not two.
4. 4Final answer: 35 + 7 = 42.

Common traps

Every wrong choice is built from a mistake children really make.

• Adding the same amount each time

  The gap between the numbers changes. Write the gaps down: if they are not equal, look at how the gaps change.

• Adding where it multiplies

  The pattern multiplies, or the other way round. Check the rule on the first two numbers and then on the last two.

  In the example: choice D (70).

• One number too far

  The choice is the number after the one asked for. Count which place in the row is the gap.

  In the example: choice E (49).