How to make test cases?

Question

Software testing

I'm doing a test task for the vacancy of a tester. The site has a registration form with 30 fields.
In the first test case, I fill them all with data.
And then the task is this - to make test cases for changing data, deleting, authorization.
Question: how to determine how many test cases should be, for example, for a change? 30 cases to do? those. one for each field? I cannot add them to one test case, since it means that they must be short.
Those. there are a lot of options to drive in there even for one field.

Answer 1

Strange condition, the tester's task is to write detailed bug reports. You can combine some fields, for example: mail, date. And the test cases will be many6 to check the length in the line (max / min), the input of English characters, incorrect mail, date, whether it is possible to write letters / numbers in one line, etc.