Base Relay
Problems in other number bases. See https://www.khanacademy.org/math/pre-algebra/applying-math-reasoning-topic/alternate-number-bases/v/number-systems-introduction for a video explanation of other number bases.
NOTE: This problem will not work if the K you get includes A, B, C, D, E or F. The code behind the scenes can not treat such a K as a base 10 number. I apologize for my limitations in programming skill to be sure such an event never occurs. If you get K to be some number like 4F, just ask for a new problem.