Convert time to decimal seconds

[Gra1]

Hi,

I am in need of help to convert a database made up of times in minutes and seconds to decimal seconds.

I have used a custom cell format to enter lap times: [m]:ss.00. Unfortunatley i have realised that i can't do the analysis that I want to in this format and now need to convert this from minutes and seconds to seconds only.

For example i have a value of 3:50.45 which i need to convert to 230.45 seconds. Any ideas on a formula as doing this manually will take days and days?!!

Thanks a lot,

Gra1.