Adding Machine Online

How to Use the Online Adding Machine

1. Type an amount on your keyboard, the numpad or the on-screen keys. Commas and a leading dollar sign are fine.
2. Press + (or Enter) to add it to the tape, or -, × or ÷ to subtract, multiply or divide the running total by it. Add a note first if you want to label the line, such as "Gas" or "Invoice 1042".
3. Take a subtotal (◇) whenever you want to check the figure so far. It prints on the tape and the count carries on.
4. Take a total (*) at the end of a list. The total prints, and the next amount starts a new group from zero.
5. Check and fix the tape. Edit or delete any line and everything after it is recalculated.
6. Print, copy or export. Print the tape, copy it as text, or download it as an Excel workbook or a CSV file.

Keyboard Shortcuts

The amount box listens for the same keys a 10-key adding machine has, so you can run down a stack of receipts without touching the mouse. The numpad's + - * / and Enter keys all work.

How an Adding Machine Differs From a Calculator

An adding machine keeps a running total and applies each amount to it as soon as you enter it. A pocket calculator waits for = and follows the order of operations. The same keys give different answers:

The adding machine order is the one you want for a tally: total the items, then apply the tax rate or split the bill. The tape shows each step, so the arithmetic can be checked line by line, which is why bookkeepers and accountants still use printing calculators.

Exact Decimal Arithmetic

Computers usually store numbers in binary, where 0.1 has no exact value, so a plain JavaScript calculator gives 0.1 + 0.2 = 0.30000000000000004 and a long list of cents can drift by a fraction of a penny. This tape stores each amount as exact decimal digits, the way you wrote it. Adding, subtracting and multiplying are exact, and 0.1 + 0.2 is 0.3. Division is the one operation that can go on forever (1 ÷ 3 = 0.333...), so it is rounded to 12 decimal places, far beyond anything a tape shows.

The decimal setting controls display only. At 2 places a total of 2.345 shows as 2.35 (rounded half away from zero, as a cash register does), but the next line is still added to 2.345. If you need each line rounded before it is added, set the places you want and type the amounts already rounded.

Send the Tape to Excel

Excel downloads an .xlsx workbook with one row per tape line: line number, operation, amount, running total and note. The amounts are real numbers, so you can sum, sort and chart them. The CSV file holds the same columns with the exact decimal values written out, ready for Google Sheets, accounting software or the CSV to Excel converter. Copy tape copies the tape as plain text, laid out like the paper roll, to paste into an email or a note.

How to Make an Adding Machine Tape in Excel

If you would rather keep the tally in a spreadsheet, put the amounts in column B (enter subtractions as negative numbers) and a running total in column C:

• In C2 enter =SUM($B$2:B2) and fill it down. The first reference is locked and the second moves, so each row totals everything above it.
• For a total, use =SUM(B2:B50); for a subtotal that ignores other subtotals in the range, use =SUBTOTAL(9,B2:B50).
• To match the tape's rounding to cents, wrap the total in =ROUND(SUM(B2:B50),2). The ROUND formula generator builds the variants.

Excel stores numbers in binary too, so a long column of cents can show a stray 0.0000000001 in a comparison. Rounding the total, as above, is the standard fix.