Result To Be A Specific Number Of Characters

What I'm looking to do with the following form is when a user inputs a certain length width and depth the output will be set to a certain number of characters. Basically looking to add a zero before an input of a number lower than 10 in two fields (product_number & product_id)

For example if a user inputs:

The output I would like to have would be:

Right now the output looks like this:

The reason for this is so when I sort my products in my shop they will go in the correct numerical order as well as making everything easier to maintain. I only need it to be 2 digits before the decimal point because the max number input will never be over 99...

Here is the code:

Code: