How to convert any duration to days in Numbers?

I have something like this | Start time (A) | End time (B) | Time passed (C) | Units done (D) | How many units per 24h (E)| | -------- | ---------- | ----------- | ---------- |------------------------- | 08:25 | 15:40 | 7h15m | 43 | **???** I can manually calculate that 7h15m = 26 100 seconds. 26 100/43 returns the time it takes to finish 1 unit = 607 seconds. 24h are 86 400 seconds. Therefore, per 24 h 142 units will be done (86 400/607 ≈ 142). I can calculate the value in E using this formula = D/(B - A) * 24 - but when C is bigger than 24 h this formula no longer works - you have to remove the multiplication with 24 then. How can this be done in Numbers?