Calculate percentages, percentage change, discounts, and tips.
Tips: Move the decimal two places left to find 10%. Divide by 10 and multiply by 2 for 20%.
Discounts: To find the sale price, subtract the discount amount from the original price.
Tax: Multiply the price by (1 + TaxRate). E.g., for 8% tax, multiply by 1.08.
To find the percentage change (increase or decrease):
Formula: $\frac{(End Value - Start Value)}{Start Value} \times 100$
If the result is positive, it's an increase. If negative, it's a decrease.
Divide the Part by the Whole, then multiply by 100.
Example: 10 is what % of 40?
$10 \div 40 = 0.25$
$0.25 \times 100 = \mathbf{25\%}$
To add VAT (or Tax) to a price:
Price + (Price × Rate)
Or simply multiply the price by 1.20 (for 20% VAT).