Question 9Aim for about 35 seconds
Find the next number in this series.
10, 56, 19, 54, 28, 52, ?
Show the worked answer
Answer: D, 37
How to work it out
- Two series take turns: 10, 19, 28 (add 9) and 56, 54, 52 (take away 2).
- The next number continues the first: 37.
Why the other options are wrong
- A (27): 27 is 10 too small. The series that goes up by 9 reaches 28 and then 37: add exactly 9 to 28.
- B (50): This is the next number of the other series (take away 2 from 52), but it is the turn of the series that goes up by 9, from 28.
- C (46): Adds 9 twice to 28. Only one step of 9 is needed to get from 28 to the next number of this series.
- E (47): 47 is 10 too big. The series that goes up by 9 reaches 28 and then 37: add exactly 9 to 28.