For positive integers m and n, there exist integers x and y such that `mx + ny = gcd(m, n)`. ...

There is an ample supply of milk in a milk tank. Mr. Fat is given a 5-liter (unmarked) container and a 9-liter (unmarked) container. How can he measure out 2 liters of milk? ...

In a special football game, a team scores 7 points for a touch down and 3 points for a field goal. Determine the largest mathematically unreachable number of points scored by a team in an (infinitely long) game. ...