How to Write Numbers in Words Correctly (for Cheques, Invoices and Exams)

Banks, businesses and exam boards all ask you to write amounts in words — and for good reason. A figure in digits can be altered with a single pen stroke: a "1" becomes a "7", a trailing zero doubles the value. Words are far harder to tamper with, which is exactly why cheques, invoices and exam papers insist on them. Handwritten figures can also smudge or bleed; spelled-out words survive far better on carbon copies and scanned documents.

Ambiguity is the other enemy. A hand-written "1,250" might be misread as "12.50" or "125.0" if the punctuation is sloppy. Written out in full, "one thousand, two hundred and fifty" leaves no room for creative interpretation.

The core rules

The conventions are simpler than most people fear:

• Hyphenate compound numbers. Twenty-one, thirty-five, ninety-nine. Any number from twenty-one to ninety-nine that combines tens and ones takes a hyphen.
• Use commas between groups. One thousand, two hundred and fifty. The comma sits between the thousand and hundred groups, just as it does in digits.
• Mind the "and." In British English, "and" comes before the final tens or ones when hundreds or thousands precede them: "one thousand, two hundred and fifty." In American English it's usually dropped: "one thousand, two hundred fifty." Either is fine as long as you're consistent — but many banks and exam boards expect the British convention.
• Capitalise the first letter on cheques. Start the amount line with a capital: "One thousand, two hundred and fifty." Some banks also want a line drawn through any blank space after the words to prevent additions.

Worked examples

• 1,250 → "one thousand, two hundred and fifty"
• A cheque for £4,018.65 → "Four thousand and eighteen pounds, sixty-five pence." Fill the remaining space on the line with a dash so nothing can be added.

Get these conventions right and you'll never have an invoice queried or a cheque bounced over a formatting technicality. For particularly long or awkward figures, a free numbers-to-words converter can double-check your wording before you commit ink to paper. It only takes a moment, and it is the cheapest form of insurance a small business owner or student can buy.