Lookup column pulling number shows 6 zeros after decimal point

Hi all.

I'm hoping someone can help me figure this out - I built a few lists in SharePoint, and the last 2 lists pull an ID number from the first list.

On the second list, the number displays with 6 zeros after a decimal point. The colum is set as a number, with 0 decimal places, no thousands separator. 

On the third list, the number shows as expected. What the heck is goin on here? 

Thanks,

Jen