Insert Digits Into A Column of Numbers

I have a column with hundreds of 7-digit numbers. I want to convert all of the numbers to 10-digit numbers with zeros inserted into the number, filling the first, fifth, and eigth digit. For instance, I have a 7-digit number xxxxxxx and I want to change it to yxxxyxxyxx where the y's are zeros. The solution I'm looking for will convert the entire column into 10-digit numbers in this manner.

I hope whoever reads this can understand it, as it is somewhat difficult to explain. I'm not sure if Excel is capable of inserting digits into numbers like this, but I sure hope so, as changing them all individually would be extremely tedious.

You can format the cells as "0"000"0"00"0"00 in place, or use an adjacent column:

=TEXT(A1,"""0""000""0""00""0""00")

Thank you for your help. Doing what you said, I managed to get the cells in the worksheet to display the numbers the way I want, but in the formula bar it still displays the number as the original 7-digit number. It seems that it treats it as the 7-digit number too, for instance if I use the find tool and try to find the 10-digit number (with the zeros added) it won't find it, but if i search for the 7-digit number then it will find it even though it displays the number as 10-digits in the cells. Is there a way to make it so that Excel not only displays it with the zeros added but treats it as the new 10-digit number?

Paul's approach will give you the same result as my second suggestion, and both give a text result. If you want a numeric result, use

=VALUE(TEXT(A1, "000""0""00""0""00"))

... and format as 0000000000 to show the leading zero.