2 Digit Multiplication

This week we started multiplying 1 digit numbers by 2 digit numbers. The method we have been focusing on this week is called Break Apart. We are using prior knowledge of place value, distributive property, addition (sometimes with regrouping) and 1 digit multiplication to solve our multiplication problems with this method.

When we are using the break apart model, we are breaking our 2 digit number apart into the tens place and the ones place. We are then multiplying the tens place by the first factor and finding that product, then multiplying the ones place by the first factor and finding that product. Once we have the product for both sets, we are taking those 2 numbers (our partial products) and adding them together to find our whole product. I promise it's not as confusing to work out as it is to read!

The answer, after adding the partial products 150 + 18 would be 168

{Here} is the link to a quick video of me working out one of the problems we did in class this week. It is also on the step-by-step page that was sent home with week along with the guided practice as extra practice as needed. {The video is an *.avi file, which may not play on some players. I am working on converting it to *.mp4 and compressing it so it will upload directly to this post.}

We have not talked about this in class yet, but it very similar to the break apart we have been doing (just without the blocks!)

In the area model, we are again breaking up our factors into their place value groups, multiplying each group in each factor by each other, then adding the totals together. This can be used with factors that go beyond 1 digit and 2 digits multiplication.

The answer after adding the partial products 150 +18 would be 168

The answer, after adding the partial products 45,000 + 900 + 180 and + 27 would be 46,737

This is a long one! The answer, after adding the partial products 70,000 + 8,000 + 0 + 60 + 14,000 + 1,600 + 0 + 12 would be 93,672