Percentage increase = [(New Value - Old Value) / Old Value] × 100
Average = Sum of all values / Number of values
Ratio = First value : Second value (in simplest form)
Shortcut 1 - Quick Percentage Calculation:
To find X% of Y, use: X × Y ÷ 100
For 25%: Divide by 4
For 20%: Divide by 5
For 12.5%: Divide by 8
Shortcut 2 - Average Estimation:
When finding average of 5-6 numbers, pick a round number close to all values. Calculate differences and adjust.
Shortcut 3 - Ratio Comparison:
To compare ratios quickly, cross-multiply. For a/b vs c/d, compare a×d with b×c.