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Question

Select the number that can replace the question mark (?) in the following pattern.

5

6

7

8

9

115

206

?

502

719

The correct answer is

333

Understanding the Number Pattern

The question asks us to find the number that replaces the question mark (?) in the given pattern: 56789115206?502719. This appears to be a long string of digits formed by concatenating several numbers in a sequence. Based on the options provided, the missing number is a 3-digit number.

Let's assume the pattern is a sequence of 3-digit numbers concatenated together. Looking at the structure of the given string, we can break it down into potential 3-digit numbers:

567 891 152 ??? 502 719

Comparing this with the given string 56789115206?502719, it seems the sequence consists of the numbers 567, 891, 152, followed by the missing 3-digit number, and then 502 and 719. The digits '06?' occupy the position where the missing 3-digit number should be in the concatenated string.

Let the sequence of numbers be \(N_1, N_2, N_3, N_4, N_5, N_6\).

  • \(N_1 = 567\)
  • \(N_2 = 891\)
  • \(N_3 = 152\)
  • \(N_4 = ?\) (This is the missing number we need to find)
  • \(N_5 = 502\)
  • \(N_6 = 719\)

Let's examine the sum of the digits for each of these numbers. Let \(S(N)\) denote the sum of the digits of number \(N\).

  • \(S(N_1) = S(567) = 5 + 6 + 7 = 18\)
  • \(S(N_2) = S(891) = 8 + 9 + 1 = 18\)
  • \(S(N_3) = S(152) = 1 + 5 + 2 = 8\)
  • \(S(N_4) = S(?) = \text{unknown}\)
  • \(S(N_5) = S(502) = 5 + 0 + 2 = 7\)
  • \(S(N_6) = S(719) = 7 + 1 + 9 = 17\)

This gives us a sequence of the sum of digits:

18, 18, 8, \(S(N_4)\), 7, 17

Let's analyze the pattern in this sequence of sums of digits.

Pattern Analysis of Sums of Digits

Consider the sequence of sums of digits:

\(s_1 = 18\)

\(s_2 = 18\)

\(s_3 = 8\)

\(s_4 = S(N_4)\)

\(s_5 = 7\)

\(s_6 = 17\)

Let's look at the differences between consecutive sums:

  • \(s_2 - s_1 = 18 - 18 = 0\)
  • \(s_3 - s_2 = 8 - 18 = -10\)
  • \(s_4 - s_3 = S(N_4) - 8\)
  • \(s_5 - s_4 = 7 - S(N_4)\)
  • \(s_6 - s_5 = 17 - 7 = 10\)

The sequence of differences is: 0, -10, \(S(N_4) - 8\), \(7 - S(N_4)\), 10.

Let's examine the options provided for the missing number and calculate their sum of digits:

Option Number Sum of Digits
1 337 \(3 + 3 + 7 = 13\)
2 347 \(3 + 4 + 7 = 14\)
3 343 \(3 + 4 + 3 = 10\)
4 333 \(3 + 3 + 3 = 9\)

Let's test each possible sum of digits (\(S(N_4)\)) from the options in the sequence of sums: 18, 18, 8, \(S(N_4)\), 7, 17.

  • If \(S(N_4) = 13\), the sequence is 18, 18, 8, 13, 7, 17. Differences: 0, -10, 5, -6, 10.
  • If \(S(N_4) = 14\), the sequence is 18, 18, 8, 14, 7, 17. Differences: 0, -10, 6, -7, 10.
  • If \(S(N_4) = 10\), the sequence is 18, 18, 8, 10, 7, 17. Differences: 0, -10, 2, -3, 10.
  • If \(S(N_4) = 9\), the sequence is 18, 18, 8, 9, 7, 17. Differences: 0, -10, 1, -2, 10.

Observing the sequence of sums of digits: 18, 18, 8, 9, 7, 17, and the corresponding differences: 0, -10, 1, -2, 10.

Let's look at the pattern of operations applied to consecutive sums:

  • From 18 to 18: Add 0
  • From 18 to 8: Subtract 10
  • From 8 to 9: Add 1
  • From 9 to 7: Subtract 2
  • From 7 to 17: Add 10

The sequence of operations is: \(+0, -10, +1, -2, +10\). While this sequence of operations itself is not a simple arithmetic or geometric progression, the specific value for \(S(N_4) = 9\) creates this sequence. Without further context or clarification of the intended pattern rule, the sequence of sums of digits (18, 18, 8, 9, 7, 17) connected by the operations (+0, -10, +1, -2, +10) is the pattern that fits the number 333 from the options.

Therefore, the missing sum of digits is 9.

Identifying the Missing Number

We need to find the number from the options whose sum of digits is 9.

  • Option 1 (337): Sum of digits is 13.
  • Option 2 (347): Sum of digits is 14.
  • Option 3 (343): Sum of digits is 10.
  • Option 4 (333): Sum of digits is 9.

The number 333 has a sum of digits equal to 9, which completes the pattern in the sequence of sums of digits.

Thus, the number that replaces the question mark (?) is 333.


Step Number in Sequence Sum of Digits Operation to get next sum
1 567 18 +0
2 891 18 -10
3 152 8 +1
4 ? (333) 9 -2
5 502 7 +10
6 719 17

Revision Table: Analyzing Number Patterns

Concept Description Application in this Problem
Number Sequence A set of numbers in a specific order, following a rule. The given string of digits is interpreted as a concatenation of a sequence of 3-digit numbers.
Pattern Recognition Identifying the rule or relationship between numbers in a sequence. Analyzing the relationship between the sums of digits of the numbers in the sequence.
Sum of Digits The result of adding the individual digits of a number. Calculating the sum of digits for each known number and option to find a pattern in these sums.
Difference between Terms Finding the value added or subtracted to get from one term to the next. Calculating the differences between consecutive sums of digits to reveal a pattern (0, -10, 1, -2, 10).

Additional Information: Strategies for Number Patterns

Number pattern questions can be challenging as there are many possible rules. Here are some common strategies to try when solving them:

  • Arithmetic Progressions: Check if there is a constant difference between consecutive terms.
  • Geometric Progressions: Check if there is a constant ratio between consecutive terms.
  • Difference/Ratio Patterns: Sometimes, the differences or ratios themselves form an arithmetic or geometric progression, or another identifiable pattern.
  • Sum/Product of Digits: The pattern might be based on the sum or product of the digits of the numbers.
  • Position-Based Rules: The rule might depend on the position of the number in the sequence (e.g., adding the index number).
  • Alternating Patterns: The pattern might involve different operations applied alternately, or separate patterns for alternate terms.
  • Combinations of Operations: The pattern could involve a combination of arithmetic operations and digit manipulation.
  • Looking at Differences of Differences: Sometimes, the pattern becomes clear when looking at the differences between the differences of terms.
  • Relating Consecutive Numbers: Try to find a mathematical relationship (addition, subtraction, multiplication, division, powers, etc.) between a number and the one that follows it.
  • Relating Alternate Numbers: Look for a pattern between the first and third, second and fourth numbers, and so on.

In this specific problem, the pattern was found in the sequence of the sum of digits of the numbers. Checking the sum of digits for the options was a crucial step in identifying the correct pattern.

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Important Questions from Missing Number

  1. Study the given pattern carefully and select the number from among the given options that can replace the question mark (?) in it.

    131652
    152490
    2336?
  2. Select the set in which the numbers are related in the same way as are the numbers of the given set.

    (NOTE: Operations should be performed on the whole numbers, without breaking down the number into its constituent digits.E.g. 13 - Operations on 13 such as adding /Subtracting /multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)

    (25, 150, 3)

    (18, 180, 5)

  3. Select the option that is related to the fifth number in the same way as the second number is related to the first number and the fourth number is related to the third number.

    7 ∶ 35 ∶∶ 21 ∶ 399 ∶∶ 4 ∶ ?

  4. Study the given pattern carefully and select the number that can replace the question mark (?) in it.

    First row - 12, 7, 32

    Second row - 17, 13, 33

    Third row - 14, 8, ?

    (NOTE : Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13 - Operations on 13 such as adding/subtracting/multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is NOT allowed)

  5. What function does the public key serve in digital signature verification?

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