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Question

What will come in place of the question mark (?) in the following equation if '×' and '+' are interchanged and '−' and '÷' are interchanged?
32 ÷ 2 × 72 − 9 + 5 = ?

This question was previously asked in
RRB NTPC 2024 CBT 1 Question Paper (28-Aug-2025) (Shift 3)
The correct answer is
70

Equation Solving with Operator Interchange

The problem requires solving a mathematical equation after interchanging specific operators. The original equation is:

$32 ÷ 2 × 72 − 9 + 5 = ?$

Operator Interchange Rules

The following operator interchanges must be applied:

  • '÷' is replaced by '−'
  • '×' is replaced by '+'
  • '−' is replaced by '÷'
  • '+' is replaced by '×'

Applying Operator Changes

Applying these rules to the original equation yields the new equation:

$32 − 2 + 72 ÷ 9 × 5 = ?$

Solving the New Equation

The new equation is solved using the order of operations (BODMAS/PEMDAS):

  1. Division: First, perform the division.

    $72 \div 9 = 8$

    The equation becomes: $32 − 2 + 8 × 5$
  2. Multiplication: Next, perform the multiplication.

    $8 \times 5 = 40$

    The equation becomes: $32 − 2 + 40$
  3. Addition and Subtraction: Finally, perform addition and subtraction from left to right.

    $32 - 2 = 30$

    $30 + 40 = 70$

Final Result

After interchanging the operators and solving according to the order of operations, the value is 70.

Therefore, the value that comes in place of the question mark (?) is 70.

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Similar Questions

  1. What will come in the place of the question mark (?) in the following equation, if '+' and '−' are interchanged and '×' and '÷' are interchanged?
    65 × 5 − 19 ÷ 3 + 25 = ?
  2. If '+' means '$\div$', '$-$' means '$\times$', '$\div$' means '+' and '$\times$' means '$-$', then find the value of $2 - 1 \times 4 \div 4 + 2$?
  3. Study the given pattern carefully and select the numbers from among the options that can replace the question marks (?).

  4. If $\nabla$ stands for operation "adding the first number to thrice the second number", then the value of $(4 \nabla 5) \nabla 6$ will be:
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  6. If '+' means 'division', '-' means 'addition', '$\times$' means 'subtraction' and '$\div$' means 'multiplication', then what will be the value of the following expression?
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Important Questions from Mathematical Operations

  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. 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

  4. 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.)

  5. If '+' means minus, '-' means multiplication, '÷' means plus, and 'x' means division, then solve the equation: 
    15 - 3 + 10 x 5 ÷ 5

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