ToolAtlasThe three homework shapes: part from whole, whole from part, and ‘up 12%, down 12% is not back to start.’ Tips and pay have their own pages.
A markdown price, a “20% off then 8.875% tax” receipt, a dashboard that says MoM +4.2% — percent arithmetic. People also try to use this box as a tax authority. We will not look up a ZIP.
US restaurant splitting is tip calculator. Paycheck tax % you enter is paycheck. Multi-year growth is compound interest.
Discounts vs tax software
“20% off” and month-over-month change are arithmetic. Raising 12% then cutting 12% does not return the start. US sales-tax holidates and filing software are out of scope. Tip splitting is the tip page; paycheck tax % is a number you type.
How to use it
- Choose the shape: % of, “x is what % of y,” or percent change.
- Type the two numbers you actually have.
- For stacked discounts, apply them one at a time in receipt order.
Honest limits
Not a POS. Not VAT invoices. Floating-point cents can be a penny off from a cash-register half-even rule.