Problem:

Finding the interval between pairs of times when they are formatted in military style (\"hhmm\").

Solution 1:

Use the TEXT function as shown in the following formula:
=(TEXT(B2,\"00\\:00\")-TEXT(A2,\"00\\:00\"))*24

Solution 2:

Use the DOLLARDE function as shown in the following formula:
=DOLLARDE(B2/100,60)-DOLLARDE(A2/100,60)