Saturday, September 14, 2013

2 digit by 2 digit multiplication

We will begin working on 2 digit by 2 digit multiplication next week. The students will learn two ways to solve a problem.

Partial Product Multiplication 

             34                              30     4
       x    25                              20     5
                                            +        80

1.   Students break each number down into expanded form.
2.   Students multiply both numbers in the ones place.
5 x 4= 20
3.   Write 20 under the equal sign line.
4.   Multiply the 5 in the ones place by the 30 in the tens place.  Write the answer directly under the 20.
5.   Multiply the bottom number in the tens place by the top number in the ones place. 20 x  4.
6.   Multiply both numbers in the tens place. 20 x 30.
7.   Add up all four numbers.

  Turtle Head Multiplication 
  This method is the standard algorithm, but it has a twist. Many students have success with this method, because the "story" helps them remember the order of events. The following video demonstrates how to correctly use this method. 

  Students will be expected to learn both the traditional and partial product method. Once mastered, they will be free to choose the method that works best for them.