Question

Which two signs should be interchanged to make the given equation correct?
16 – 18 $\times$ 216 $\div$ 432 + 40 = 20

• A. + and –
• B. $\times$ and $\div$
• C. $\times$ and +
• D. $\div$ and –

Hint:

Look for the division sign first. In the original equation, $216 \div 432$ results in $0.5$. Since the final answer is a whole number (20), we likely need to move the division sign to a place where it divides perfectly.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
In mathematical operation puzzles, we must test the options to see which swap results in the correct equality, always following the BODMAS (Brackets, Orders, Division, Multiplication, Addition, Subtraction) rule.

Step 2: Key Formula or Approach:
Test Option (B): Interchange $\times$ and $\div$. The equation becomes: $16 - 18 \div 216 \times 432 + 40 = 20$.

Step 3: Detailed Explanation:
Applying BODMAS to the modified equation: 1. Division: $18 \div 216 = \frac{18}{216} = \frac{1}{12}$ 2. Multiplication: $\frac{1}{12} \times 432 = 36$ 3. Substitute back: $16 - 36 + 40$ 4. Addition and Subtraction: $16 + 40 - 36 = 56 - 36 = 20$ Since $20 = 20$, the interchange is correct.

Step 4: Final Answer:
The signs that should be interchanged are $\times$ and $\div$.