Question
What will come in the place of ‘?’ in the following equation, if ‘+’ and ‘-‘ are interchanged and ‘×’ and ‘÷’ are interchanged?
5 × 39 ÷ 39 + 39 - 5 = ?
This question was previously asked in
RRB ALP 2025 CBT 2 Wiremen Question Paper (28-Jul-2026) (Shift 2)
The correct answer is
-29
The problem requires solving a given equation after interchanging specific mathematical operators.
Interchanging Operators
The original equation is:
\(5 × 39 ÷ 39 + 39 - 5 = ?\)
The rules for interchange are:
- '×' is interchanged with '÷'
- '+' is interchanged with '-'
Applying these interchanges to the original equation, we get the new equation:
\(5 ÷ 39 × 39 - 39 + 5 = ?\)
Solving the New Equation
To find the value of '?', we solve the new equation using the standard order of operations (BODMAS/PEMDAS): Brackets, Orders, Division and Multiplication (from left to right), Addition and Subtraction (from left to right).
- Division: Calculate \(5 \div 39\). This is \(\frac{5}{39}\).
- Multiplication: Multiply the result by 39. So, \(\frac{5}{39} \times 39 = 5\).
- The equation now simplifies to: \(5 - 39 + 5 = ?\).
- Subtraction: Calculate \(5 - 39 = -34\).
- Addition: Calculate \(-34 + 5 = -29\).
Therefore, the value that comes in the place of '?' is -29.
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Important Questions from Maths Operations
- If 37 D 18 E 84 F 21 = 51 and 57 D 28 E 90 F 15 = 79, then 14 D 17 E 8 F 4 = ?
- This question is based on the five, three-digit numbers given below.
(Left) 194 582 419 149 825 (Right)
(Example- 697 – First digit = 6, second digit = 9 and third digit = 7)
What will be the resultant if the third digit of the highest number is added to the second digit of the lowest number? - If 1 is added to each odd digit and 2 is subtracted from each even digit in the number 4813576, what will be the difference between the highest and the lowest digits in the number thus formed?
- If '+' means '-', '-' means '×', '×' means '÷', '÷' means '+', then what will come in place of the question mark (?) in the following equation?
316 - 2 ÷ 37 + 436 × 4 = ? - If 1 is added to each odd digit and 1 is subtracted from each even digit in the number 21673458, what will be the product of the greatest and smallest digit in the new number thus formed?
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