Meaning & use
check digit
Last updated
Meanings
nouncountabletechnical
An extra digit added to a number so that a machine can check whether the number was entered correctly.
Grammar: Countable: one check digit, two check digits. It is often used after 'a' or 'the'.
Patterns
- a check digit for something
- calculate a check digit
- the check digit is wrong
The last number of a barcode is a check digit that helps the scanner detect errors.
If you type an account number wrongly, the check digit will usually not match.
The software calculates a check digit and adds it to the end of the membership number.
nouncountablemathematicscomputing
A digit used in a mathematical formula to test whether a longer sequence of digits is valid.
Grammar: Countable and technical; often appears in phrases like 'check digit algorithm' or 'check digit calculation'.
Patterns
- check digit algorithm
- check digit calculation
- verify something using a check digit
The check digit algorithm catches most typing mistakes in credit card numbers.
Students learned how a check digit can be used to validate an ISBN.
The check digit calculation is simple once you know the formula.
Word forms
| plural | check digits |
|---|
Common combinations
- calculate a check digit
- The program will calculate a check digit for every order number.
- check digit algorithm
- This check digit algorithm is used in many banking systems.
- the check digit is incorrect
- The form was rejected because the check digit was incorrect.
- add a check digit
- You need to add a check digit to the end of the code.
- verify a number using a check digit
- The website verifies your ID number using a check digit.
Synonyms and how they differ
- checksum
- Checksum is a broader term for a value used to detect errors in data, while a check digit is specifically a single digit used for the same purpose.
- validation digit
- Validation digit is a less common synonym that emphasizes the digit's role in checking validity.
Word family
Commonly confused: check digit or check number?
check digit vs check number
A check number is the number printed on a bank check, while a check digit is an extra digit used to verify a number's accuracy.
Practice
A check digit is added to a number mainly to ______.
Choose one answer.
The purpose of a check digit is to help a machine detect mistakes in a number, so 'detect errors when the number is entered' is correct. 'Make the number longer' is wrong because length is not the goal; the digit is for checking.
Make it your own
Write a sentence using “check digit”, then check it and compare it with the examples above.