To convert to base 2, divide by 2 each time
if the the quotient is 1 put 1 and if 0 put 0 till you reached to the end
see the following steps:
557/2 = 278 and the remaining is 1
278/2 = 139 and the remaining is 0
139/2 = 69 and the remaining is 1
69/2 = 34 and the remaining is 1
34/2 = 17 and the remaining is 0
17/2 = 8 and the remaining is 1
8/2 = 4 and the remaining is 0
4/2 = 2 and the remaining is 0
2/2 = 1 and the remaining is 0
1/2 = 0 and the remaining is 1
Beginning from the lower to the upper
So, 557 of base 10 = 1000101101 of base 2