I need to find the time difference.
I have a exacle sheet which I have made **cells format as number** before going to past the data in that exacel.

I have starttime in A column end time in B column like:

```
A--------------- B ---------- Time_diff_min(C)
20101104190507-------20101104190531
20101126145506-------20101126190644
20101120133943-------20101120185104
```

. . . like this but I need exact time difference in minutes.

I tried to find make difference like =(B1-A1) formula, but it does not given exact value because as it is in number format. but I need in mm:ss