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Question

By interchanging the given two signs which of the following equation will NOT be correct?
$+$ and $\div$
I. $27 \div 3 - 18 \times 3 + 9 = 24$
II. $12 \div 8 \times 12 + 16 - 7 = 19$

This question was previously asked in
SSC CGL 2025 Tier 2 Paper 1 Question Paper (19-Jan-2026)
The correct answer is
Only II

Interchanging Signs: Equation Analysis

The question asks us to swap the mathematical signs '+' and '÷' in the given equations (I and II) and determine which equation becomes incorrect after the swap. We will use the standard order of operations (BODMAS/PEMDAS) to evaluate the equations.

Equation I Analysis

Original Equation I: $27 \div 3 - 18 \times 3 + 9 = 24$

Interchange '+' and '÷':

  • The equation becomes: $27 + 3 - 18 \times 3 \div 9$
  • Applying BODMAS/PEMDAS:
  • Multiplication first: $18 \times 3 = 54$
  • Division next: $54 \div 9 = 6$
  • The expression simplifies to: $27 + 3 - 6$
  • Addition: $27 + 3 = 30$
  • Subtraction: $30 - 6 = 24$

The resulting value is $24$, which matches the right-hand side of the original equation. Therefore, Equation I is correct after interchanging the signs.

Equation II Analysis

Original Equation II: $12 \div 8 \times 12 + 16 - 7 = 19$

Interchange '+' and '÷':

  • The equation becomes: $12 + 8 \times 12 \div 16 - 7$
  • Applying BODMAS/PEMDAS:
  • Multiplication first: $8 \times 12 = 96$
  • Division next: $96 \div 16 = 6$
  • The expression simplifies to: $12 + 6 - 7$
  • Addition: $12 + 6 = 18$
  • Subtraction: $18 - 7 = 11$

The resulting value is $11$. The original right-hand side was $19$. Since $11 \neq 19$, Equation II is NOT correct after interchanging the signs.

Conclusion

Based on the analysis, only Equation II becomes incorrect when the signs '+' and '÷' are interchanged.

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Similar Questions

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

  2. If 'x' means 'addition', '-' means 'division', '/' means 'subtraction' and '+' means 'multiplication', then which of the equation is correct?

  3. If '+' stands for multiplication, '-' stands for addition, 'x' stands for division, then what is the value of 128 + 9 - 16 x 4 = ?

  4. If 'x' means addition, '-' means division, '÷' means subtraction and '+' means multiplication, then which of the equations is correct?

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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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