Alien Fingers

Alien Fingers Using the most powerful telescope ever made, scientists observe a class of young aliens on a planet millions of light years away. On the blackboard, their teacher has written these equations: 13 + 15 = 31 10 x 10 = 100 6 x 3 = 24 How many fingers do they have? (We count in base ten. What do they count in?) Show how you know, and create a new problem in this base to share with the class.