Question
Select the correct combination of mathematical signs that can sequentially replace the * signs and balance the given equation.
100 * 25 * 35 * 15 * 5 * 180
A. ×, –, +, ÷, =
B. +, –, ÷, ×, =
C. –, +, ÷, ×, =
D. –, +, ×, ÷, =
Answer: D. –, +, ×, ÷, =
Solution:
According to BODMAS rule:
Given equation 100 * 25 * 35 * 15 * 5 * 180
Option 1: Using the combination ×, –, +, ÷, =
100 × 25 – 35 + 15 ÷5 =180
100 × 25 – 35 + 3 =180
2500 – 35 + 3 =180
2503 – 35 =180
2468 = 180 (LHS ≠ RHS)
Option 2: Using the combination +, –, ÷, ×, =
100 + 25 – 35 ÷ 15 × 5 = 180
100 + 25 – 2.34 × 5 = 180
100 + 25 – 11.7 = 180
125 – 11.7 = 180
113.3 = 180 (LHS ≠ RHS)
Option 3: Using the combination –, +, ÷, ×, =
100 – 25 + 35 ÷ 15 × 5 = 180
By BODMAS rule
100 – 25 + 2.34 × 5 = 180
100 – 25 + 11.7 = 180
111.7 – 25 = 180
86.7 = 180 (LHS ≠ RHS)
Option 4: Using the combination –, +, ×, ÷, =
100 – 25 + 35 × 15 ÷ 5 = 180
100 – 25 + 35 × 3 = 180
100 – 25 + 105 = 180
205 – 25 = 180
180 = 180 (LHS = RHS)
Hence, the answer is “–, +, ×, ÷, =”.