Login ID is invalid?
– Check your spelling* and make sure no extra spaces before or after.
*NOT case-sensitive. Either lowercase or uppercase is ok;
– Confirm you’re on correct KooBits ProblemSums Login Page, which should be shown as https://problemsums.koobits.com on your browser's address bar;
– Forgot your Login ID? You should Check Login ID Format (Singapore school only);
– Your Login ID this year might be different from previous year, so please Check Login ID Format (Singapore school only);
– Do you have a valid KooBits account this year?
If not sure, email firstname.lastname@example.org to enquire.