TASK: Try and use a secure pin number. This includes pins for your phone, individual apps, banking etc. Pin numbers like 1234, 1111, 9999 etc should be avoided. Numbers that include your date of birth or other obvious information should also be avoided. Ideally use a longer pin, like 6 digits for example. Better still is to use a password that includes numbers, upper and lower case letters with a symbol thrown in too.
WHY: Attackers can guess easy pin numbers. If they do they have access to your bank account, phone etc. If you use the same pin across multiple services then it is even more important to use a secure pin. Computers can 'brute force attack' your login details. A four number pin is trivial for even a desktop computer, just adding a few letters/numbers makes it exponentially harder to crack.