Page 763 - AP Computer Science A, 7th edition

17. (A) Quick method: Convert each hex digit to binary. 3 Dhex
= 0011 1101 (where D equals 13 in base 10)
= 111101bin
Slow method: Convert 3Dhex to base 10.
3Dhex = (3)(161) + (D)(160) = 48 + 13
= 61dec
Now convert 61dec to binary. Write 61 as a sum of descending powers of 2:
61 = 32 + 16 + 8 + 4 + 1
= 1(25) + 1(24) + 1(23) +
1(22) + 0(21) + 1(20) = 111101bin