Correct Answer : C
Step 1 : 21 % 2 = 1
and 21 / 2 = 10
Step 2 : 10 % 2 = 0
and 10 / 2 = 5
Step 3 : 5 % 2 = 1
and 5 / 2 = 2
Step 4 : 2 % 2 = 0
and 2 / 2 = 1
Step 5 : 1 % 2 = 1
and 1 / 2 = 0
Now write the results of all %
operations in reverse order (i.e., from Step 5 to Step 1)
So answer is 10101