How to write a US check correctly.
A US check has six parts, and the amount line uses a cents convention that trips up first-time writers. Here is each field, in order, done right.
The six fields
From top to bottom: the date (top-right), the payee on "Pay to the order of", the amount in figures in the box, the amount in words on the long line, an optional memo (bottom-left), and your signature (bottom-right). Miss the signature and the check is void; mismatch the words and figures and it may be returned.
The amount in figures
Write the figure tight against the dollar sign in the box, including cents: 3,250.00. Leaving a gap invites alteration, so keep it snug and, for a whole amount, still write the .00.
The amount in words — and the cents
This is the part people get wrong. Write the dollars in words, then the cents as a fraction over one hundred. The word "Dollars" is usually preprinted at the end of the line. So 3,250.00 is written "Three Thousand Two Hundred Fifty and 00/100", and 3,250.07 is "Three Thousand Two Hundred Fifty and 07/100". Note two things: there's no "and" inside the number itself in American style (it's "Three Thousand Two Hundred Fifty", not "... and Fifty"), and the only "and" is the one joining dollars to cents. Draw a line from the end of the words to the printed "Dollars" so nothing can be inserted.
Why cents are a fraction, not words
Writing cents as "07/100" rather than "Seven Cents" is compact and hard to alter — a fraction over a fixed denominator can't easily be extended. For a whole amount, "00/100" (or "No/100") makes clear there are no cents. The US check converter produces this line for any dollar amount.
Memo and signature
The memo is optional but useful — "March rent", an invoice number. Sign exactly as your bank holds your signature on file. A mismatch here is a common reason for a check being refused.