This should have been a separate topic as you are not trying to search for the existence of a substring.
Nonetheless, the issue here is that you are using “100%” as a mathematical value. You can only use numerical value, such as 100, 0, -100, 10.01, etc…
I cannot suggest anything as I cannot see your data. The % sign is actually an operator. It represents the mod operator, which gives you the remainder of a division. For example, 502 % 100 is 2.
So, if we look at your statement, it’s incomplete if you are using the % operator. That is why it complains that it’s expecting an operand after the %, but found ‘)’ instead.