Select the number from among the given options that can replace the question mark (?) in the following series.

69, 55,  26, 13, ? 

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RRB NTPC CBT-I Official Paper (Held On: 28 Dec 2020 Shift 1)
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  1. 2
  2. 5
  3. 3
  4. 4

Answer (Detailed Solution Below)

Option 4 : 4
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RRB NTPC CBT-I Official Paper (Held On: 4 Jan 2021 Shift 1)
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Detailed Solution

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The given series: 69, 55,  26, 13, ?

The logic follows here:

Previous number digits multiply with each other + 1 = next number.

The pattern followed here is:

6 × 9 + 1 = 55

5 × 5 + 1 = 26

2 × 6 + 1 = 13

1 × 3 + 1 = 4

Hence, the next number of the series would be "4".

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