73 ÷ 1 = 73 R0
Let's divide 73 by 1.

Step 1:
1 goes into 7 7 times with a remainder of 0.
Write down 7 as next digit of of the result. 
Result so far: 7
Subtract 7 from 7 to get 0.
Bring next digit (3) of the dividend behind the 0 and repeat the process: 3 / 1

Step 2:
1 goes into 3 3 times with a remainder of 0.
Write down 3 as next digit of of the result. 
Result so far: 73
Subtract 3 from 3 to get 0.

The final result is 73 with a remainder of 0.