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Question

What will come in place of question mark (?) in the following number series?

31, 32, 36, ?, 61, 86

This question was previously asked in
RBI Assistant Prelims Memory Based Paper (27 March 2022) (Shift 2)
The correct answer is

45

Number Series Pattern Analysis: 31, 32, 36, ?, 61, 86

We need to find the missing number in the given series: 31, 32, 36, ?, 61, 86.

Let's examine the differences between consecutive terms to identify a pattern:

  • Difference between the second and first term: $32 - 31 = 1$
  • Difference between the third and second term: $36 - 32 = 4$

The differences observed are 1 and 4. We can recognize these numbers as perfect squares:

  • $1 = 1^2$
  • $4 = 2^2$

This suggests that the difference between consecutive terms might be increasing squares of consecutive integers.

Let's test this hypothesis:

  • First term = 31
  • Second term = First term + $1^2$ = $31 + 1 = 32$
  • Third term = Second term + $2^2$ = $32 + 4 = 36$
  • Missing term (Fourth term) = Third term + $3^2$ = $36 + 9 = 45$

Now, let's verify if this pattern holds for the remaining terms:

  • Fifth term = Missing term + $4^2$ = $45 + 16 = 61$
  • Sixth term = Fifth term + $5^2$ = $61 + 25 = 86$

The calculated terms match the given series (31, 32, 36, 45, 61, 86). Therefore, the pattern of adding consecutive squares ($1^2, 2^2, 3^2, 4^2, 5^2, ...$) is correct.

The missing number in the series is 45.

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Similar Questions

  1. What will come in place of question mark (?) in the following number series?

    2, 5, 11, 23, 44, 77, ?

  2. What will come in the place of question mark (?) in the following number series?

    3, 6, 18, ?, 630, 6930

  3. What should come in place of the question mark ‘?’ in the following number series?

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Important Questions from Number Series

  1. What will come in place of question mark (?) in the following number series?

    2, 5, 11, 23, 44, 77, ?

  2. What will come in the place of question mark (?) in the following number series?

    3, 6, 18, ?, 630, 6930

  3. What should come in place of the question mark ‘?’ in the following number series?

    60, 40, 50, ?, 180, 460

  4. A series is given with one term wrong. Select that wrong term from the given alternatives.

    J12, M24, P48, S96, U192

  5. In the following question, select the related number pair from the given alternatives.

    144 : 400 :: ?

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