Ways to Flatten A Perl Array in Scalar Context

I recently started learning perl and have a question that I'm not finding a clear answer to on the Internet. say I have something like this,

@arr = (1, 2, 3);
$scal = "@arr"
# $scal is now 123.

Is the use of quotes the only way to flatten the array so that each element is stored in the scalar value? It seems improbable but I haven't found any other ways of doing this. Thanks in advance.