SSC CGL (Prelims) Reasoning: Mathematical Operations questions with solutions

Q1. What will come in place of the question mark (?) in the following equation, if '+' and '-' are interchanged and '×' and '+' are interchanged? 152 + 6 + 1617 × 7 - 77 = ?

1. 587
2. 578
3. 758
4. 785

Answer: 758

Using the interchange rule, the operators are replaced as instructed and the expression is then evaluated in the new form. The final value comes out to 758.

Q2. Which two numbers, not digits, should be interchanged to make the given equation correct? 6 × 3 + 8 + 2 + 21 + 5 × 4 - 14 + 7 = 53

1. 8 and 4
2. 3 and 5
3. 2 and 4
4. 21 and 14

Answer: 21 and 14

Interchanging 21 and 14 changes the expression so that its value becomes 53. No other listed swap makes the equation true.