We have already looked at the traditional way to multiply multi-digit numbers. With this lesson, I would like to expand your ‘tool belt’ of knowledge and give you another method or strategy to use when multiplying. My goal is for you to be able to use the partial products method today. Remember, you should practice this method, master it and then decide which strategy or method makes the most sense to you and then use it. The object of my instruction is to give you multiple ways to find the product of a number equation. By the end of next week’s lesson, you will have learned three strategies and then you can pick out the one that works best for you. Or better yet, develop your own and share it with the class!
When using the partial products method, you will want to remember two things: make sure you are adding all the partial products and numbers together correctly and make sure you are using the correct place value–align your numbers exactly! This is the key to successfully using this method.
Who loves addition? Me too! This is the beauty of the partial products method–you get to use addition. This approach allows you to break the multi-digit number into smaller pieces or chunks, multiply them separately and then add the chunks all together. The number will not seem quite so BIG or scary this way! You worked with expanded notation at the beginning of the school year, so this should seem familiar to you.
Let’s take a look at this power point presentation:
Now for some practice, try to do the following problems on your own or with your table buddy. Remember to set them up vertically.
1. 46 x 6 2. 68 x 4 3. 93 x 7
4. 324 x 5 5. 5235 x 8 6. 3349 x 3
When you have finished these, please create your own 5 problems and solve for homework. For extra credit, write word problems to go along with your partial products multiplication problem.
Some of you may ask, well, how do you use this method when you are multiplying with all multi-digit factors? Great question! Please check out this video to see how you can cross multiply when you have multi-digit factors.