Return partial int value when matching two number sets

I am working with data like the following:

8443913000 | 39211900

8483409000 | 84834029

I want to see if the first 5 numbers or the first 6 numbers match. However, I would like to return the digits instead of returning a text value, i.e. "Same" or "Not Same". Currently I am just using an if statement:

if(left(A1,5)=left(B1,5),"Same","Not Same")

While I may need to use INDEX/MATCH I am just not sure about the output.

Thank you

Edit: The right column is the master number and the left column is the slave number.