You are doing a vstring assignment here. The . characters are not concatenating your digits together like you thought.

$a = 1.2.3;
          
print $a; #printing junk characters
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If you were using strings then it would do it but not numbers. This is what you were thinking would happen.

$a = "1"."2"."3";
          
print $a;
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A better example for working with a normal number would be this,

$a = 1.20;
          
print $a;
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1.20 is a proper number, would you expect it to be '1.20' or 120? Vstrings are a little different however.