How do I get numbers to provide a sum of times where total is greater than 24 hours?

I have to keep track of flight time for my job as a pilot. The most important value is total time flown per year, but I cannot figure out how to get numbers to sum times when the total is greater than 24. MsExcel does it by using a time format that brackets the hour value. This tells excel to ignore the 24 hour limit. How do I do this in Numbers? or do I have to purchase Excel to get the job done?