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Question

Which two signs should be interchanged to make the following equation correct? 
$56-74\times17+391\div23 = 1297$

The correct answer is
+ and -

Question Type: Arithmetic Reasoning

Step-by-step Solution:

The given equation is: \(56 - 74 \times 17 + 391 \div 23 = 1297\)

Let's evaluate the equation using the standard order of operations (BODMAS/PEMDAS):

  1. Division: \(391 \div 23 = 17\)
  2. Multiplication: \(74 \times 17 = 1258\)
  3. Subtraction and Addition: \(56 - 1258 + 17 = -1185\)

The result is -1185, which is not equal to 1297. We need to interchange two signs to make the equation correct.

Let's try interchanging the '+' and '-' signs:

\(56 + 74 \times 17 - 391 \div 23 = ?\)

  1. Division: \(391 \div 23 = 17\)
  2. Multiplication: \(74 \times 17 = 1258\)
  3. Addition and Subtraction: \(56 + 1258 - 17 = 1297\)

The equation now holds true: \(1297 = 1297\)

Why other options are incorrect:

  • Option 1 (\(\div\) and \(\times\)): Interchanging these would significantly alter the result and not lead to 1297.
  • Option 3 (\(\times\) and \(-)\): This would result in a large negative number.
  • Option 4 (\(\div\) and +): This would also result in a value far from 1297.

Core Logic/Pattern: The core logic is to systematically try interchanging the arithmetic operators to find a combination that satisfies the equation. The order of operations must be carefully followed.

Therefore, the correct answer is to interchange the '+' and '-' signs.

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Important Questions from Bodmas Rule

  1. The value of 90 ÷ 20 of 6 × [11 ÷ 4 of {3 × 2 - (3 - 8)}] ÷ (9 ÷ 3 × 2) is:

  2. The value of 1800 ÷ 20 × {(12 - 6) + (24 - 12)} is:

  3. The value of 20 ÷ 5 of 8 × [9 ÷ 6 × (6 - 3)] - (10 ÷ 2 of 20) is:

  4. The value of \(\left( {18 \div 2\;of\frac{1}{4}} \right)\; \times \;\left( {\frac{2}{3} \div \frac{3}{4}\; \times \;\frac{5}{8}} \right) \div \left( {\frac{2}{3} \div \frac{3}{4}of\frac{3}{4}} \right)\) is:

  5. The value of 18 ÷ [26 - {25 - (15 - 5) ÷ 2}] of 12 + 2 - 2 ÷ 4 × 16 is:

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