Excel custom format with letters and numbers

I've searched in posted items with no success.

When I create a custom format like ##-##-## and I type 458586 I get: 45-85-86

But, if the code I enter is C45858 I get C45858, and not C4-58-58 which is what I wanted.

What is the custom format I should creat to get C4-58-58 when I type C45858??

Thanks in advance!!

Well if the letter C is always a constant (never changing), you can do a custom format like this: "C"0-00-00

When you enter the number into the cell you would only enter the numeric portion of the numnber as in 45858 which will produce the results of C4-58-58.

Hope this helps.