To convert integer to binary, start with the integer in question and divide it by 2 keeping notice of the quotient and the remainder. Continue dividing the quotient by 2 until you get a quotient of zero. Then just write out the remainders in the reverse order.
In this case, the integer is 100.
Let Q stand for quotient and R for the remainder in each step.
Then
100 ÷ 2 gives Q=50 and R=0
50 ÷ 2 gives Q=25 and R=0
25 ÷ 2 gives Q=12 and R=1