Today we started to talk about multiplying by tens. So we're starting to multiply two digit numbers times other two digit numbers. But what's a little bit easier about these two digit factors is that all of them have one that's a multiple of ten. So 80, 30, 60, 20, 50, 90, ten. These are all multiples of ten. So when we're multiplying by a multiple of ten, we can forget about the zeros for a second that are at the end. So multiply 22 times 8 and then put your zero at the end. Okay? So we forgot about this for a few minutes just to multiply 22 times 8, and then we can put our zero at the end. So two times 8 was 16. I put my 6 here, regrouped, brought my one up here, two times 8 is 16 plus one is 17. So 22 times 8 is 176. 22 times 80 is 1760 all I did was put that zero back on the end. For number three, instead of trying to do 30 times 52. Do 52 times three and then put your zero on the end after you multiply. Number four is a little different because we have two multiples of ten. So you can do 6 times two and then put two zeros at the end. Number 5 35 times four then put your zero at the end there. Number 6 is similar to number four. You'll do one times 9 and then put your two zeros at the end. Okay? Down at the bottom, the word problems are exactly the same you're doing 12 times 20. So do 12 times two and then put your zero at the end. Number 9, you're doing 48 times ten. So do 48 times one and then put your zero at the end.
