Calculation playbook

Percentage Playbook: Discounts, VAT, Tips and Splits

Percent means per hundred. That one idea powers sale prices, VAT, tips, allowance splits and everyday budget decisions.

The base move

The core formula is number times percentage divided by 100. So 20% of 150 is 150 times 20 divided by 100, which equals 30. The Percentage Calculator is the direct version of that move.

Discounts are multipliers

A 20% discount means you pay 80% of the original price. A 50% discount means you pay half. But two discounts do not simply add together. A 20% discount followed by 10% off is not the same as one 30% discount because the second discount applies to the reduced price.

Try this with the Discount Calculator and the Double Discount Calculator. It is a useful sale-tag reality check.

VAT works differently when you remove it

Adding VAT multiplies the net price by one plus the VAT rate. Removing VAT divides the gross price by one plus the VAT rate. That division is the part people often miss because the tax is already inside the displayed total.

Percentages make small choices visible

Tips, allowance splits and subscriptions are more interesting when the percentage turns into a real amount. Use Tip Splitter for group bills, Allowance Split Calculator for save-give-spend practice and Subscription Cost Calculator for recurring totals.

Play it: one price, four stories

Start with 100 as your test price. Open the Discount Calculator and calculate 20% off. Then open the Double Discount Calculator and try 20% followed by 10%.

Next, open the VAT Calculator and add 20% VAT to 100. Finish with the Tip Splitter using a bill of 100, tip of 20 and 4 people. Same starting number, completely different money stories.