Nine and a half times. *** you can put it fully nine times. You reach 18 like this. But you have 1 more to go until 19! So, just cut the 2 in half to get 1, and put that in!
It can only fully go into 19, 9 times (2*9=18 and 2*10=20). However if you can use decimals or fractions 2 can go into 19 9.5 times or 9 1/2 times (9.5 is equal to 9 1/2. 9.5*2=19)