How do you prevent a 0 from disappearing in a cell in Excel

I’m sure everyone has had this problem of that first zero disappearing in a cell in Excel and how to format it to stay. Well how do you make it stay if you are cutting and pasting numbers into a new worksheet from another program? I’ve tried formating all the cells before and after pasting, etc. but nothing seems to work. Can this be done? And if so, how? These are just a series of 9 numbers all starting with a zero, but we need the zero to show. thanks!