Problem: In our number system the base is ten. If the base were changed to four you would count as follows: 1,2,3,10,11,12,13,20,21,22,23,30,… The twentieth number would be:
Answer Choices:
A. 20
B. 38
C. 44
D. 104
E. 110
Solution:
20=1⋅42+1⋅41+0⋅40;∴ the required number is 1104;
or
20÷4 yields 5 and remainder 0;
5÷4 yields 1 and remainder 1;
∴2010 becomes 1104.