Also, keys( %BOOK ) won't give you a number but will show you 'name','email','comments', and 'posttime', not a number.

That is not correct. keys in a scalar context returns the number of keys:

my %hash = ( foo => 1, bar => 2, baz => 3 );
print "There are " . keys( %hash ) . " keys\n";

# output
There are 3 keys
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