Just four procedures were used to produce a design. How was it done? Can you be systematic and elegant so that someone can follow your logic?
The country Sixtania prints postage stamps with only three values 6 lucres, 10 lucres and 15 lucres (where the currency is in lucres).Which values cannot be made up with combinations of these postage. . . .
Caroline and James pick sets of five numbers. Charlie chooses three of them that add together to make a multiple of three. Can they stop him?
How many ways can the terms in an ordered list be combined by repeating a single binary operation. Show that for 4 terms there are 5 cases and find the number of cases for 5 terms and 6 terms.
Find all real solutions of the equation (x^2-7x+11)^(x^2-11x+30) = 1.
Prove that you cannot form a Magic W with a total of 12 or less or with a with a total of 18 or more.