Quant Methods and Tricks

Method 1: Convert words into equations

Do not keep aptitude questions in English. Convert each line into a number statement.

Example:

A number is increased by 20% and becomes 240.

Equation:

1.2x = 240
x = 200

Method 2: Use options

For MCQs, option substitution is often faster than formal algebra.

Use options when:

• equation setup is long,
• answer choices are simple,
• question asks for original value.

Method 3: Assume convenient values

Use 100 when percentages are involved.

Example:

Price increases by 20%, then decreases by 20%.

Assume 100:

• after +20% = 120
• after -20% = 96
• net loss = 4%

Method 4: Work problems using LCM

If A takes 12 days and B takes 18 days, take total work as LCM = 36 units.

• A does 3 units/day
• B does 2 units/day
• together = 5 units/day
• time = 36/5 = 7.2 days

This avoids fractions.

Method 5: Average shift

If average of 10 numbers is 50, sum = 500. If one number 40 is replaced by 70, sum increases by 30, so average increases by 3.

New average = 53.

Method 6: Ratio scaling

If ratio is 3:5 and difference is 20:

5x - 3x = 20
2x = 20
x = 10
numbers = 30, 50

Method 7: Speed unit discipline

Before solving speed problems, make units consistent.

Most common mistake:

72 km/h = 72 × 5/18 = 20 m/s

Do not mix km/h with meters.

Method 8: DI fast scanning

For data interpretation:

1. Read the question.
2. Locate only required row/column.
3. Calculate approximate value first.
4. Match nearest option.

If options are far apart, approximation is enough.

Method 9: Elimination in quant

Eliminate options by:

• units,
• parity odd/even,
• last digit,
• approximate magnitude,
• impossible negative/decimal values.

Method 10: Time budget

If a question takes more than 75 seconds in a 30-question/30-minute section, mark and move.

Easy questions missed due to time pressure cost more than one hard question.