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Question

In the following number-pairs, the second number is obtained by applying certain mathematical operations to the first number. Which numbers should replace X and Y so that the pattern followed by the two numbers on the left side of :: is the same as that on the right side of :: ?

(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.)

X : 649 :: 956 : Y

This question was previously asked in
RRB NTPC 2024 Undergraduate CBT 1 Question Paper (29-Aug-2025) (Shift 1)
The correct answer is

X = 894, Y = 711

Number Pairs Pattern Analysis

This question asks us to identify a consistent mathematical pattern between the first and second numbers in two pairs: 'X : 649' and '956 : Y'. The key rule is that the operations must be applied to the whole number itself, not its individual digits. We need to find the values for 'X' and 'Y' that follow the same rule.

Identifying the Mathematical Operation

Let's first examine the second pair, '956 : Y', using the provided correct answer for Y, which is 711.

  • The first number is 956.
  • The second number (Y) is 711.

To find the relationship, we can check the difference between these two numbers:

\(956 - 711 = 245\)

This suggests that the pattern might be subtracting 245 from the first number to obtain the second number in the pair.

Applying the Pattern to Find X

Now, let's apply this identified pattern (subtracting 245) to the first pair, 'X : 649'. We use the correct answer provided for X, which is 894.

  • The first number is X (which is 894).
  • The second number is 649.

Let's verify if subtracting 245 from X gives us 649:

\(894 - 245 = 649\)

This calculation confirms that when X is 894, subtracting 245 results in 649, matching the pattern.

Conclusion: Determining X and Y

Based on the analysis:

  • The pattern involves subtracting 245 from the first number to get the second number.
  • For the pair 'X : 649', if X = 894, then \(894 - 245 = 649\).
  • For the pair '956 : Y', if Y = 711, then \(956 - 245 = 711\).

Therefore, the values X = 894 and Y = 711 correctly follow the established mathematical pattern.

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Similar Questions

  1. Select the set, from the given options, in which the numbers are related in the same way as are the numbers of the following sets.

    (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.)

    (6, 13, 78)

    (5, 22, 110)

  2. If + means -, - means ×, × means ÷, ÷ means +, then what will come in place of the question mark (?) in the following equation?

    28 - 6 ÷ 4 + 14 × 14 = ?

  3. Which two numbers should be interchanged to make the given equation correct?

    75 ÷ 5 + 15 × 4 - 17 × 3 + (60 ÷ 6) × 10 = 100

    (Note: Interchange should be done of the entire number and not individual digits of a given number.)

  4. If ‘A’ stands for ‘\(\div \)', ‘B’ stands for ‘x', ‘C’ stands for ‘+', ‘D’ stands for ‘-', what will come in the place of the question mark '?' in the following equation?
    225 B 15 A 15 C 125 D 225 =  ?

  5. Select the set in which the numbers are related in the same way as are the numbers of the following sets. 
    (NOTE : Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 3 - Operations on 3 such as adding /deleting /multiplying etc. to 3 can be performed, Breaking down 3 into | and 3 and then performing mathematical operations on 1 and 3 is not allowed.) 
    (144, 12, 6) 
    (210, 15, 7)

  6. Select the set in which the numbers are related in the same way as are the numbers of the following sets. 
    (NOTE : Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 3 - Operations on 3 such as adding /deleting /multiplying etc. to 3 can be performed, Breaking down 3 into | and 3 and then performing mathematical operations on | and 3 is not allowed.) 
    (9, 6, 56) 
    (7,8, 58)

  7. If A means +, B means -, C means x, D means \(\div \), then what will come in place of the question mark (?) in the following equation?
    18 D 2 A 4 C 5 B 15 = ?

  8. If 'A' stands for '+', 'B' stands for '×', 'C' stands for '+' and 'D' stands for '-', then what will come in place of the question mark (?) in the following equation? 

    47 D 25 A 5 C 2 B 9 = ?

  9. If + means -, - means ×, × means ÷, ÷ means +, then what will come in place of the question mark (?) in the following equation?

    22 - 5 ÷ 3 + 12 × 3 = ?

  10. Which two numbers should be interchanged to make the given equation correct?

    186 - 82 + (129 ÷ 3) − 6 × 8 + (31 - 19) × 2 = 85

    (Note: Interchange should be done of entire number and not individual digits of a given number.)


Important Questions from Mathematical Operations

  1. Which two numbers (not digits) should be interchanged to make the given equation correct? 

    21 × 8 – 18 + (64 ÷ 2) + 32 = 64

  2. The two expressions on either side of the equal sign will have the same value if two numbers on the left-hand side are interchanged and two signs on the right-hand side are interchanged. What are those two numbers (not digits) and the two signs? 

    9 × 1 ÷ 3 + 8 – 7 = 12 ÷ 3 + 2 × 33 – 13

  3. Select the set, from the given options, in which the numbers are related in the same way as are the numbers of the following sets.

    (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.)

    (6, 13, 78)

    (5, 22, 110)

  4. If + means -, - means ×, × means ÷, ÷ means +, then what will come in place of the question mark (?) in the following equation?

    28 - 6 ÷ 4 + 14 × 14 = ?

  5. Which two numbers should be interchanged to make the given equation correct?

    75 ÷ 5 + 15 × 4 - 17 × 3 + (60 ÷ 6) × 10 = 100

    (Note: Interchange should be done of the entire number and not individual digits of a given number.)

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