Competitive Exams
Shortcuts for Banking, SSC, and CAT.
Exam Shortcuts
In competitive exams, speed is everything. Here are the most common shortcuts.
Percentage Change Rule
If A is 1/n more than B, then B is 1/(n+1) less than A.
Example: A is 25% (1/4) more → B is 20% (1/5) less.
Successive Change
Net % Change = A + B + (AB/100)
For discounts, use negative values.
-20 and -10 → -30 + 2 = -28% (28% Discount).
Solved Examples
Example 1: Price increases by 25%
Question: How much to reduce consumption to keep expense same?
• Price up by 25% = 1/4.
• Consumption must go down by 1/(4+1) = 1/5.
• 1/5 = 20%.
• Answer: 20%.
Example 2: CI - SI Difference
Question: Diff for 2 years at 5% on 1000.
• Difference is only on the interest of interest.
• Rate is 5%. Interest on 5% is 0.25%.
• 0.25% of 1000 = 2.5.
• Answer: 2.5.
