How should I formulate a validation error message for a number field?
- A number is expected.
- A number is required.
- The value should be a number.
- Number is not valid.
- Invalid number.
- Value is not a number.
There are a few things you can do up front, such as be clear that the input expects a number. Or simply not accept inputs that aren't numbers (if they type characters just ignore them).
To dissect your options a bit more: