One way:

=(TEXT(B1,"0\:00")-TEXT(A1,"0\:00"))*1440

In article .com,
wrote:

I need help with formating the time with colon when time entered
without colon in to two different columns. Then calculate the
difference between two times.
For example:

enter in colum A Colum B
difference (in minutes)

850 converts to 08:50 855 convets to 08:55
5
855 08:55 900 09:00
5
1150 11:50 1158 11:58
8

Can anyone help me with this please?

Thanks
GG