Download Strategies for solving two-digit by two

Multiplication:
Strategies for solving two-digit by two-digit multiplication problems.
1. Break apart method. This method involves breaking apart the numbers and
multiplying them separately.
Example: 22 x 13. First separate 22 (20 + 2) then separate 13 (10 + 3). Now
multiply.
10 x (20 + 2); 3 x (20 + 2)
20 x 10 = 200; 2 x 10 = 20; 3 x 20 = 60; 3 x 2 = 6
*Now add the sums together to get the solution to the problem 22 x 13.
200 + 20 + 60 + 6 = 286
2. Box method. This method involves the breaking apart method, but uses the
graphic organizer of a box to help keep your facts organized.
Example: 22 x 13.
20
2
In this box multiply 20 x
10
200
In this box multiply 20 x 3
60
In this box multiply 10 x 2
10
20
In this box multiply 3 x 2
6
3
*Now add all the numbers in the boxes together to get the answer to the
equation 22 x 13.
200 + 20 + 60 + 6 = 286
3. U.S. Algorithm. Stack the numbers right on top of each other and draw a line
under the bottom number. Multiply the ones digit on the bottom with the top
numbers. Then multiply the tens place digit on the bottom with the top numbers.
Add the two sums together. It is very important to write neatly with this method
so as not to forget which digit is in which place.
Example: 22 x 13
22
X 13
___________
66 (3 x 2, 3 x 2)
+ 220 (write a zero to indicate you are starting with the tens spot, (2x 1, 2 x1)
___________
286