auto fill custom format numbers

I have the following list of numbers

0000 0000 0000 0000 0000 0100
0000 0000 0000 0000 0000 0101
0000 0000 0000 0000 0000 0102

and I need to continue the list to

0000 0000 0000 0000 0000 0326

I tried dragging by the grip in the bottom right hand corner but it changes the first didit only.

I tried to put it the numbers in the format

100
101
102

and using a custom format number to put in the extra zeros. This worked fine until I used a countif (or it may of been a lookup) statement in my code to look for 0000 0000 0000 0000 0000 0100 and it can't find it as the number is 100.

Is there away around this that will save me typing in an awful lot of zeros.

Thanks