Sniper Mode: Per-Cent

1. Fraction - Percentage Table (Memorize)

• 1/2 = 50%, 1/3 = 33.33%, 1/4 = 25%.
• 1/5 = 20%, 1/6 = 16.66%, 1/7 = 14.28%.
• 1/8 = 12.5%, 1/9 = 11.11%, 1/10 = 10%.
• 1/11 = 9.09%, 1/12 = 8.33%.
• 3/8 = 37.5%. 5/6 = 83.33%.

2. A is what % of B?

• Formula: (A / B) * 100.
• A is what % MORE than B? (A-B)/B * 100.
• Sniper Rule: Whatever comes after "than" or "of" goes in Denominator.

3. Successive Change (AB Formula)

• Net % Change = A + B + (AB/100).
• Use for: Population growth, Length/Breadth increase area change.
• Ex: Price up 10%, then up 20%. Net = 10+20 + (200/100) = 32%.

4. Problem Types

• Election: Total = Valid + Invalid. Winner wins by margin. Margin = (Winner % - Loser %).
• Consumption: Price UP 25%. How much cons DOWN to keep exp same?
  • Trick: 25% = 1/4. Increase (+) 1/4 -> Decrease (-) 1/(4+1) = 1/5 = 20%.
• Pass/Fail (Venn): n(A U B) = n(A) + n(B) - n(A n B).