Select the option that correctly completes the series: 21, 57, 32, 48, 39, ____
43
43 is correct.
Differences between consecutive terms: \(+36, -25, +16, -9\).
These are \(6^2, 5^2, 4^2, 3^2\) with alternating signs, so the next difference is \(+2^2 = +4\).
The rule is: go up by a perfect square, then down by the next smaller perfect square, and so on. After going down by 9, the series must go up by 4.
Missing term: \(39 + 4 = 43\).
Similar Questions
Select the option that correctly completes the series: 8, 9, 13, 22, 38, ____
Select the option that correctly completes the series: 1330, 728, 342, 124, ____
Select the option that correctly completes the series.
88, 98, 83, 103, 78, ?
Select the option that completes the series.
12, 12, 13, 26, 28, 84, ?
Complete the series by filling in the blank in the correct manner.
15, 45, 70, 90, 105, ?
Select the option that correctly completes the series.
37, 50, 65, 82, 101, ?
Select the option that completes the series.
2, 4, 8, 14, 22, ____
Select the option that completes the series by filling in the blank.
90, 96, 105, 117, 132, _____
Select the option that will complete the series.
33, 45, 69, 105, 153, ____
Select the option that correctly completes the series: 41, 46, 56, 73, 99, 136, ____
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
