A document that is calculated

Change a few lines on the left and the paper on the right follows; then hit "Save as image" and send it. The paper is not laid out in HTML — it is drawn stroke by stroke on a canvas, so every line's position, every right-aligned column and the spacing of the totals are worked out as coordinates, and it looks the same on everyone's phone. The amount in words is calculated too (the cheque form, cents over 100). Nothing here is uploaded anywhere — saving the image is a local act.

Line items one per line: name · unit price · qty

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Heading Your name Contact Bill to Number Date Discount Tax % Signed Stamp Currency Note

The words line is the hardest arithmetic on the page. English numbers are not digit-by-digit: 0–19 each have their own word, the tens have their own, "and" only appears inside a hundred, and every group of three digits takes a scale word — unless the whole group is zeros, in which case it takes none. The cents are written as a fraction over 100 because that is the cheque convention: "45" can have a zero added to it, "45/100" cannot. amountInWords() is thirty lines and was checked against 0.01, 10.05, 1,001, 100,000,000 and 1,234,567.89.