Problem 6
In the base ten number system the number 526 means 5 * 10^2 + 2*10 + 6. In the Land of Mathesis, however, numbers are written in the base
r. Jones purchases an automobile there for 440 monetary units (abbreviated m.u.). He gives the salesman a 1000 m.u. bill, and receives, in change, 340 m.u. The base
r is?
