Calculate the number of ordered triples (A1, A2, A3) such that:
A1 ∪ A2 ∪ A3 = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} A1 ∩ A2 ∩ A3 = ∅
Write your answer as 2a3b5c7d where a, b, c, d are non-negative integers.
The numbers 1, 2 and 3 have been placed at the corners of a triangle. Arrange the numbers 4, 5, 6, 7, 8, and 9 on the sides, so that the numbers along each side (including the corners) add up to 17.
Arrange all the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 to give four different square numbers. (You make a square number when you multiply something by itself, so 49 is square because it is 7 times 7)
In the last column what are the four numbers:
2 5 9 7 4 1 6 6 6 5 3 5 _ _ _ _
