To calculate a discount, use the "X% of Y" calculator. Enter the discount percentage as X and the original price as Y. The result will show the discount amount. Subtract this from the original price to get the sale price.

Use the "X% of Y" calculator. Enter the tip percentage (usually 15-20%) as X and the bill amount as Y. The result will be the tip amount to add to your bill.

Use the "Percentage Change" calculator. Enter the original value as "From" and the new value as "To". The calculator will show the percentage increase (or decrease if the value went down).

Use the "X% of Y" calculator. Enter the tax rate as X and the purchase amount as Y. The result will be the tax amount to add to your purchase.

Use the "X is what % of Y" calculator. Enter the part value as X and the total value as Y. The result will show what percentage the part is of the total.