The error is from use strict - which is good. Also check you have use warnings.

This type of problem is (almost) always due to bad code which isn't a syntax error. For instance, a stray double-quote on a line above could be wrapping my $num in a string. Mismatched parentheses, brackets or braces around this code are likely candidates. A missing semicolon to terminate a statement is another possibility. There could be other reasons.

The line where the error is reported is important - you haven't shown that here.

If you can't find the problem through simple visual inspection, try commenting out a line near the error and see if you get different (more useful) messages.

I also find it good practice to keep a mental catalogue of silly mistakes I make often and check for those first. For example, I often don't release the Shift key quickly enough, resulting in a colon, rather than a semicolon, at the end of the line, e.g.

$var1 = $hash{$key}:
$var2 = some_sub(@args):
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Use of an editor with syntax highlighting can also sometimes help in this situation. I understand that is a personal choice and some people prefer not to use syntax highlighting.