Math Questions : How many fingers do Martians Have?

the highest digit visible is 9 so the number system base is at least 10.

10*10=100 is true in all bases so there's no information there

3*3=9 is consistent in any base greater than or equal to 10

4*4=15 cannot be in base 10 so the base of their number system is larger than 10

the entire number 15 is in the form 1*base^1 + 5^base^0

you know that in decimal 4*4=16 the lowest digit of an integer in any base is always "the one's column" or "base^0 = 1"

so you're safe computing 16-5 = the value of the next column since the digit in that base^1 column is 1.

16-5 = 11

so the number is in base 11 and if you presume that all civilizations count on their fingers and that they use standard indo-arabic numerals, it would mean that martians have 11 fingers.

you can check this by plugging the martian digits into the equation:

1*11^1 + 5*11^0 =

1*11 + 5*1 =

11 + 5 =

16 which is the correct decimal value for 4*4