Question

Which two number should be interchanged to make the following equation correct?

$72\div{9}\times{8} + 6-5 = 100$

• A. 9 and 6
• B. 9 and 8
• C. 6 and 8
• D. 9 and 5

Answer 1

Answer:

A. 9 and 6

Solution:

The logic followed here is :-

By using BODMAS RULE :

Option 1) : 9 and 6

Given equation : 72 ÷ 9 × 8 + 6 – 5 = 100

After interchanging the symbols in the given equation the equation formed is as follows : 72 ÷ 6 × 8 + 9 – 5 = 100

⇒ 72 ÷ 6 × 8 + 9 – 5 = 100

⇒ 12 × 8 + 9 – 5 = 100

⇒ 96 + 9 – 5 = 100

⇒ 105 – 5 = 100

⇒ 100 = 100

LHS = RHS

Option 2) : 9 and 8

Given equation : 72 ÷ 9 × 8 + 6 – 5 = 100

After interchanging the symbols in the given equation the equation formed is as follows : 72 ÷ 8 × 9 + 6 – 5 = 100

⇒ 72 ÷ 8 × 9 + 6 – 5 = 100

⇒ 9 × 9 + 6 – 5 = 100

⇒ 81 + 6 – 5 = 100

⇒ 87 – 5 = 100

⇒ 82 ≠ 100

LHS ≠ RHS

Option 3) : 6 and 8

Given equation : 72 ÷ 9 × 8 + 6 – 5 = 100

After interchanging the symbols in the given equation the equation formed is as follows : 72 ÷ 9 × 6 + 8 – 5 = 100

⇒ 72 ÷ 9 × 6 + 8 – 5 = 100

​⇒ 8 × 6 + 8 – 5 = 100

​⇒ 48 + 8 – 5 = 100

​⇒ 56 – 5 = 100

​⇒ 51 ≠ 100

LHS ≠ RHS

Option 4) : 9 and 5

Given equation : 72 ÷ 9 × 8 + 6 – 5 = 100

After interchanging the symbols in the given equation the equation formed is as follows : 72 ÷ 5 × 8 + 6 – 9 = 100

⇒ 72 ÷ 5 × 8 + 6 – 9 = 100

⇒ 14.4 × 8 + 6 – 9 = 100

⇒ 115.2 + 6 – 9 = 100

⇒ 121.2 – 9 = 100

⇒ 112.2 ≠ 100

LHS ≠ RHS

Hence, the correct answer is "9 and 6".