To make 2/21 = 42, you have to multiply 2/21 by 2. You multiply both sides of 2/21 so you now have 4/42, which is equal to 2/21. You now have 4/42 which is saying 4/42 presidents or, 4 out of 42 president have no kids.
if you add all the numbers together you get 27.6! follow the rule: if its higher then 5 round if its not then dont round. since it was a 6 we round and get 28.