Partial products for multiplying 2 by 1 digits
About this video
This video uses partial products to multiply 67 x 9. It multiplies 9 by the ones (9 x 7 = 63) and by the tens (9 x 60 = 540), then adds the partial products to get 603.
You'll be able to
- break a 2-digit number into tens and ones to multiply.
- find partial products and add them to get the final product.
Key words
- partial product
- The answer to one smaller part of a multiplication, like 9 x 7 or 9 x 60.
- ones place
- The digit that tells how many ones; in 67 it is 7.
- regroup
- To trade 10 of one place for 1 of the next place, like 10 tens for 1 hundred.
Transcript
- [Instructor] We're told to use partial products to multiply 67 times nine. And so they wrote 67 times nine here and they broke out some of the steps. And so let's just think about what's happening. It looks like Step 1, we're doing a partial product of nine times something.
And then Step 2, we have another partial product of nine times 60. So this right over here, the nine times 60, which is equal to 540, that's when essentially you took the nine and you multiplied it times the six tens right over there. So that's nine times the 60.
So Step 1, the way you could think about it is this is going to be nine times the one's place. So this is going to be nine times seven. And what is nine times seven? That is going to be 63. And so if you take nine times seven and you add that to nine times 60, well, then, you're going to get what nine times 67 is.
And so let's add all of this together. Three plus zero is three. Six plus four is 10. We can write a zero there and regroup that one. And then 100 plus 500 is 600. So that is 603. Or you might recognize, 540 plus 63, 540 plus 60 is 600, plus another three is 603, and we're done.
Video © Khan Academy, used under CC BY-NC-SA. Watch on Khan Academy. Puzzicle is not affiliated with Khan Academy.