system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do contracts write all numbers twice? i.e. "No less than three (3) business days' notice"
gpt
Legally, numbers written out in words take precedence over numerals. For example, if you have "four hundred twenty-seven (327)" in a contract, a court would enforce the written out amount.

The reason for that is that it's harder to mess up a written amount by making a single typo. The reason people also include the numerals is that they're easier to read. So written out numbers are a cautionary measure and numerals are for ease of reading.