A number format changes how a value looks, never the value itself. 0.125 can show as 0.125, 13%, 12.5% or $0.13, and every formula still uses 0.125.
The quickest ways in, on the Home tab or the keyboard:
- Percent: Ctrl+Shift+5. It multiplies the display by 100, so 0.15 shows as 15%. Typing 15 into a percent cell gives 1500%; type
15% or 0.15 instead.
- Currency: Ctrl+Shift+4 shows $1,234.50.
- Date: Ctrl+Shift+3. A column of numbers like 46083 is usually dates that lost their format.
- Increase / Decrease Decimal (Alt, H, 0 and Alt, H, 9) add or remove decimal places one at a time.
When a cell fills with #####, the number is too wide for the column. Widen the column (double-click the right edge of its header) and the number comes back.