Video Transcript
What is the number that when multiplied by 28 gives 22120? What is the number that when multiplied by 28 gives us 22120?
In order to find out this missing value, we’ll need to take 22120 and divide it by
28. So we put 22120 inside our division box, then we put 28 on the outside. First we ask, can 28 go into 22? Because 28 is bigger than 22, that’s not possible. Now we have to ask how many times can 28 be divided into 221. In my head, I’m thinking 28 is about 30. I know that 30 times seven equals 210. So I think maybe seven is a good place to start.
What is seven times 28? We start by multiplying seven times eight. Seven times eight is 56. We write down our six and carry our five. And then we multiply seven times two which equals 14 and add five to that. 14 plus five equals 19. Seven times 28 equals 196. And now we need to subtract 196 from 221. In the hundreds place, we have one minus six, but that doesn’t work. So we borrow from our thousands place, and we have now one thousand and 11
hundreds.
Now we can say 11 minus six equals five. In the thousands place we have the same problem. We can’t take nine from one. We borrow from our 10 thousands place, leaving us with one ten thousands and 11
thousands. 11 minus nine equals two. One minus zero equals zero. From there we bring down our next digit, a two. And we want to know how many times does 28 go into 252.
In my head, I’m thinking that 28 times 10 equals 280, and 252 is less than 280, but
not by much. So I want to see if 28 times nine equals 252. To find out, I need to multiply 28 times nine. Nine times eight equals 72. We write down our two and carry our seven. Nine times two equals 18, plus seven. 18 plus seven equals 25.
And that means 28 times nine is exactly 252. When we subtract 252 from 252, we get zero. We have one remaining digit in our division problem. Bring down our zero. 28 goes into zero zero times. Using division, we’re able to see that our missing number is 790. 790 times 28 equals 22120.
