Value based analysis

Hi Guru's

I have a requirement to fill a column 'Value' based on column '% Units'. Where the data in the '% Units' is of the form 2.3, 4.2 8.7 and so on for respective accounts.

I have a condition that if the '% units' is b/w 0-4.9 and 5-9.9 10-14.9, 15-19.9 the values in the 'Value' column are to be filled accordingly wit pre determined values as 1, 2, 3 and 4 respectively.

Pls. suggest me how to fill the 'Value' column as such.

Thank you and appreciate your help.