In the video, the guy had a different way of doing division, and than proved his method by adding in a weird way. When he divided seven into twenty-eight, seven couldn't go into two but it did go into eight one time so he wrote down one and then placed the two in front of the one to make it twenty-one, and seven went into that three times, so the answer was thirteen. Then he checked his answer by writing thirteen seven times and adding each column of numbers and he put down the overall total which was twenty-eight. Another problem that I figured out is that four goes into thirty-six eighteen times. I just tried out different even numbers until one worked. The guy was wrong because he didn't carry his numbers to the other column when he was adding, and when he did the long division, he put that seven goes into eight once, instead of seven into twenty-eight.