Find the next number in the given sequence 1, 3, 11, 31, 69, ________.
131
When the terms grow irregularly, look at the differences and then at the differences of the differences.
Step 1 — First differences: 3 − 1 = 2, 11 − 3 = 8, 31 − 11 = 20, 69 − 31 = 38.
Step 2 — Second differences: 8 − 2 = 6, 20 − 8 = 12, 38 − 20 = 18, which rise by 6 each time; the next is 24.
Step 3 — Next first difference = 38 + 24 = 62, so the next term = 69 + 62 = 131. The values 125, 130 and 132 would need differences of 56, 61 and 63, which break the pattern.
131 option is correct.
Important Questions from Number Series
What will come in place of question mark (?) in the following number series?
2, 5, 11, 23, 44, 77, ?
What will come in place of question mark (?) in the following number series?
31, 32, 36, ?, 61, 86
What will come in the place of question mark (?) in the following number series?
3, 6, 18, ?, 630, 6930
What should come in place of the question mark ‘?’ in the following number series?
60, 40, 50, ?, 180, 460
A series is given with one term wrong. Select that wrong term from the given alternatives.
J12, M24, P48, S96, U192
