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Data Validation
Data Validation restricts the type of data that can be entered into a cell, helping prevent typos and inconsistent entries before they happen.
Setting Up a Dropdown List
Data tab -> Data Validation -> Allow: List -> Source: Noida,Delhi,GurugramThis turns the cell into a dropdown, letting users pick only from the specified options instead of typing free text.
Restricting Number Ranges
Allow: Whole Number -> Data: between -> Minimum: 0, Maximum: 100Useful for fields like percentages or scores, where any value outside a valid range should be blocked.
Custom Validation with a Formula
Allow: Custom -> Formula: =AND(LEN(A2)=10, ISNUMBER(A2))Custom formulas make it possible to enforce more specific rules, such as requiring a phone number to contain exactly 10 digits.
Input Messages and Error Alerts
The Input Message tab can show a helpful tooltip when a cell is selected, and the Error Alert tab can block or warn on invalid entries with a custom message.
Data validation doesn't clean up existing bad data - it prevents new bad data from being entered, which is why it's most effective when set up before data collection begins.