Identify the missing number or letter within the series.
97, 94, ?, 79, 67, 52
Answer: A
Explanation: The difference between the numbers in this series increases by -3 each time: -3, -6, -9, etc. Therefore the third number in the series is 88.
16, 18, 21, ?, 30
Answer: D
Explanation: The difference between the numbers in this series increases by 1 each time: 2, 3, 4, 5, etc. This will produce a difference of 4 between 21 and the next number in the series, which is therefore 25.
Identify the missing number at the end of the series.
20, 16, 12.8, 10.24, ?
Answer: B
Explanation: The difference between the numbers in this series is (minus) the number divided by 5. For example 20/5 = 4. 20-4 = 16. Then 16/5 = 3.2. 16-3.2 = 12.8. To obtain the final number in the series 10.24/5 = 2.04. Therefore subtract 2.05 from 10.24 to give 8.19.
2, 5, 9, 14, 20, ?
Answer: C
Explanation: The difference between the numbers in this series increases by 1 each time: 3, 4, 5, 6, etc. This will produce a difference of 7 between 20 and the next number in the series, which is therefore 27.
798, 777, 756, 735, ?
Answer: E
Explanation: The numbers in this series decrease by 21 each time. Therefore the next number is 714.
