[mysql] How to convert Varchar to Double in sql?

I have problem with my query when I was trying to convert the varchar field to double (numeric). I have this sql statement:

SELECT fullName, CAST(totalBal as numeric(9,2) FROM client_info ORDER BY totalBal DESC

Actually I want to display the values of totalBal in descending order. But since that field is in varchar, the resultset is sometimes wrong. This is the resultset when I tried to query using this statement:

SELECT fullName, totalBal FROM client_info ORDER BY totalBal DESC 

Resultset is:

The sorting of totalBal is not correct. So I decided to convert the varchar to numeric so that it might be sorted perfectly. Any idea?

This might be more desirable, that is use float instead

SELECT fullName, CAST(totalBal as float) totalBal FROM client_info ORDER BY totalBal DESC