(####) = (HH:MM) in 24 Hour Clock help, thanks

Hello Excel Pro's! This may be a remedial answer, but I can't find what I'm looking for. This may be because I don't know what the proper term is.
I'd like to place a value of, lets say 11:00am, but on my keyboard, I don't want to type the ( and/or (am). So I'd like to type (1100) and have the sheet automatically know that the input is 11:00am and for it to look like = 11:00
This is because I'm working with a 24hour clock, so no need for am or pm.
Then I need the formula to calculate the total time. 11:00 to 12:00 = one hour (01:00) then *24 = 1.0 (all decimals rounded to 1 decimal, ie .0-.9; 1.2 or 4.7)

Same would go for a date. Entered = 32018 but the computer would see it as 03/20/2018 and it would look like 20-Mar-18.

Row 1: Example
Entered into A1 = 1100 but looks like 11:00
Entered into B1 = 1200 but looks like 12:00
C1 = A1 + B1 or B1 - A1 = 01:00
D1 = C1 * 24 = 1.0

Row 2: Example
Entered into A2 = 1215 but looks like 12:15
Entered into B2 = 1512 but looks like 15:12
C2 = A2 + B2 or B2 - A2 = 02:57
D2 = C2 * 24 = 3.0

The tricky part is when the clock rolls over into the next day as example row 3
Row 3: Example
Entered into A3 = 2345 but looks like 23:45
Entered into B3 = 0143 but looks like 01:43
C3 = A3 + B3 or B3 - A3 = 01:58
D3 = C3 * 24 = 2.0

Row 4 = formulas?

0	a	b	c	d
1	11:00	12:00	01:00	1.0
2	12:15	15:12	02:57	3.0
3	23:45	01:43	01:58	2.0
4	=hh:mm or ##\:##	=hh:mm or ##\:##	Solved! =B3+--(B3<A3)-A3	=C*24

For the date input 4418 = 4-Apr-18 not solved yet.

Thanks for any help in advance.

That seems like it works pretty good and that way if there's no value entered it will just equal 0.
So the next part would be the inputs.
How do I make it where I can enter in 2345 and have it look like 23:45 and the sheet knows it's that time of 23:45 or 11:45pm in HH:MM format?
I have a number keypad, and it's a pain to reach back over and type Shift : every time.
Same for the date thing. Entered = 3202018 but the computer would see it as 03/20/2018 and it would look like 20-Mar-18.

formating it in HH:MM or [H]:mm is not working.

Thanks!

custom format A1 & B1: ##\:##
Total time:

Please Login or Register  to view this content.

Custom format ##\:## worked for entering but the the new formula calculations are either now wrong or #value!
It also now displays a big boarder around the box which I do not want.

B3+--(B3<A3)-A3 worked previously manually typing the : symbol in the time.

But now there's a new problem with the *24 to get the decimal not being correct.

there are times where the decimals are .1 off.

attachment added to post #4

1:

running into an issue where the number is rounding to the nearest hour.
example
start 16:00, end 19:23=03:23
the formula is solving 03:00

When I put those numbers in my wb, I get 3:23 not 03:00
2:

Also, instead of the month number I need to month name abbreviated. April = Apr
not the number Apr = 4
Is there a way to tell it 1 = Jan... 4 = Apr and so on?

No, you can't do that with custom formats. It only modifies the appearance of the date data by adding the "-" between the numbers