Divide the part by the whole
Multiply the result by 100
Use the formula `=A1/B1` and format the cell as Percentage
Use the formula `=A1/B1*100` if you want the percentage as a number
Use `=SUM(A1:A10)/B1` to find a percentage from a total
Use `=(New Value-Old Value)/Old Value` to find percentage change
Format cells as Percentage from the Home tab
Increase or decrease decimal places if needed