whats 9+10

Question

 I'm thinking 21... 

Answer 1

You're correct if you mean a number system with base 9

then 21 means 2x9 +1 = 18+1 = 19 in base 10

but if you mean the usual base 10 number system, then 9+10 = 19

In base 8, 23 would be the answer where 2x8+3 =16+3=19 when you convert to base 10

in base 7, 25 would be correct with 2x7+5 =14+5=19

in base 6, 31 = 3x6+1 = 19

base 5, 34 converts to 3x5+4 = 19

base 4, 43 might seem to be 4x3+7= 19, but you never have more than a digit 3 in base 4, same as base 10's largest digit is 9. so for base 4 100 means 4^2=16 and 103 converts to 19 in base 10

base 2, 1000 converts to 2^4 =16 and 1011 means 19 in base 10

19 1's strung together: 1111111111111111111 might be another way to represent 19

base 1 though can't use a digit greater than 0

base 10 has 9+10 =19

base 11 needs another digit, call it A then 10 means 11 and 18 in base 11 means 11+8 = 19 in base 10

base 24 would have the usual 9 digits plus maybe 13 letters where A=10, B=11, and N= 23 in base 24, N=23

in any base >23, N=23. base 5 billion, N=23

base 12 would have 17 = 19 in base 10

1 in 17 means 12, 12+7=19

base 13 would be 16 representing 19 in base 10

so 21 or a lot of answers are right depending on what base number system you use