Need to add semi colon in time numbers

[RustyB]

I need a formula for taking a time number like 1435 and making it 14:35
I know there is a simple way to do it but I can't figure it out. An
help would be greatly appreciated

 

[Luke M]

=TIMEVALUE(LEFT(A2,2)&":"&RIGHT(A2,2))

Format the cell then as desired.

 

[David Biddulph]

=--TEXT(A1,"00\:00") and format as time to suit.