How Sum hours in Numbers and keep the sum in time format after 23:59?

Hi everyone,

I'm struggling with a sum in time on numbers, I arranje everything but I can't found the correct way to sum all my hours and keep it in the time format for exemple:

sum 23:30 with 100:00 = 123:00

but I can't put it that way and always convert to days and hours.

Can Someone help me ??