1. a, b, c and d are four distinct positive integers such that the product of any two of them is any multiple of 12. Find the least possible value of a + b + c +d.

2. My twelve-hour clock has four digits, two for the hours and two for the minutes. The minutes are shown with leading zeros but the hours are not. Upside down, the digits 0, 1, 2, 5, 6, 8 and 9 read 0, 2, 3, 5, 9, 8 and 6 respectively. One day, I made a phone call on the appointed time and learned that it was too early. Then, I realized that I had read the clock upside down. If you know by how much I was early, you will know the time when I made the call. The time I should have made the call was….

In order to solve these math problems, you should be able to show you are a thinker. IB student should be able to use thinking skills critically and creatively to understand problems in order to reach a solution/decision.