Identify the missing number at the end of the series.
72, 63, 54, 45, ?
Answer: C
Explanation: The numbers in this series increase by -9 each time. The next number is 36.
97, 94, 88, 79, 67, ?
Answer: A
Explanation: The difference between the numbers in this series increases by 3 each time: -3, -6, -9, -12 etc. This will produce a difference of -15 between 67 and the next number in the series, which is therefore 52.
28, 35, 42, 49, 56, ?
Answer: B
Explanation: The numbers in this series increase by 7 each time. The next number is 63.
11, 16, 26, 41, ?
Explanation: The difference between the numbers in this series increases by 5 each time – 5, 10, 15, etc. This will produce a difference of 20 between 41 and the next number in the series, which is therefore 61.
7, 11, 15, 19, ?
Explanation: The numbers in this series increase by 4 each time. The next number is 23.
