Create a Data Entry Validation Rule

Stop impossible entries before they happen: only whole numbers here, only 0–50% there.

You will learn to

• Allow only whole numbers in a range
• Limit decimals to a range
• Understand what validation rejects

How it works

Select the cells, choose Data → Data Validation, and pick what to Allow — Whole number, Decimal, Date, Text length or a List — plus limits such as between 1 and 100. Entries that break the rule are rejected with a message, which keeps shared sheets clean.