Copy specific number of digits from column to column

Hi all,
I have what is hopefully a simple question. I have an excel table filled with customer numbers and addresses (column A is customer number and B is address).
Example of column A customer numbers
Column A
2014564.001
2014589.002
2016897.025

This table will link to an ARCGIS mapping program to associate certain things to a physical address. The first 7 digits in the customer number (column A) will never change (they are associated with the physical address). The last 3 digits after the decimal will change based on customer - which I will not need.

What I want to do is copy the first 7 digits from column A to column C. I can then use column C as my link to the physical address. I have tried to just format the column to a number with no decimal, however it will round up the last number in some instances. I will update this table once a month and was hoping there is an easy way to do this (there are thousands of customer numbers and addresses).
Thanks in advance!