Multiplication Mania: 1-2 Digits

Lesson Plan - Get It!

Audio:

• Did you know multiplication is a shortcut to addition?

Multiplication is the repeated addition of equal groups. The number of equal groups and the number in each group are the factors. Numbers that are multiplied together are called "factors." The answer is called the "product." Multiplication is shown in three special ways:

Notice that in the example of the raised dot, the dot is not like a decimal point. It is almost floating in between the two numbers.

Multiplication is a faster way to do repeated addition. In the example above, "four times five" really means the number 4 written 5 times, or added to itself five times. Another way to show this would be 4 + 4 + 4 + 4 + 4. By knowing your multiplication facts or using a multiplication chart, you can solve multiplication problems.

• How well do you know your multiplication facts?

Learning and remembering multiplication facts can make your math life easier. Sometimes they are called "times tables." If you are able to quickly recall multiplication facts up to 12, it can help you solve multiplication problems. If not, you can also use a multiplication table.

Take a few minutes to explore MathIsFun.com's The 12 Times Table and practice finding facts. As you move over the numbers within the table, look at the multiplication fact that shows up on the screen. Read through the tips below the table to learn tips and patterns to become better at multiplication.

Some multiplication problems cannot be answered with only a multiplication table. When multiplying a two-digit number by a one- or two-digit number, we have to multiply twice. There are a few ways to do this, but a common way is called "partial product." Take a look at two examples of using partial product:

28 x 6 =

1. Multiply the ones place: 6 x 8 = 48. Notice how the 8 is written down and the 4 is carried over to the tens place.
2. Now multiply the tens place of one factor, 28, and the other factor, six: 2 x 6 = 12, and don't forget to add in the amount we carried over: 12 + 4 = 16.

Another way to think of this problem would be to break it up into smaller numbers:

28 = 20 + 8, then multiply each of those numbers by 6: 20 x 6 = 120 and 6 x 8 = 48; add the two sums together, and you will get 168.

28 x 6 =

1. Multiply the ones place. 6 x 8 = 48. Notice how the 8 is written down and the 4 is carried over to the tens place.
2. Now, multiply the tens place of the top factor, 28, and the other factor, 6: 2 x 6 = 12, and don't forget to add in the amount we carried over: 12 + 4 = 16. These steps were similar to the problem above. But now we have a number in the tens place in the bottom number.
3. Notice how there is an asterik in the next line of our work. This is a place holder spot, since we are moving in to multiply the tens place next. Some people write just a 0, or an X.
4. Now, multiply the tens place of the bottom number, 1, by the ones place of the top number. 1 times 8 is 8.
5. Now, multiply the tens place of the bottom number, 1, by the tens place of the top number, 2. 1 times 2 is 2.
6. Now, add the products together:

If this method is difficult for you, you might want to learn more about The Lattice Method, from The Animated Classroom:

Discuss with an adult or teacher:

• How are addition and multiplication related?
• Discuss when it would be helpful to be able to multiply numbers quickly.

Now, you are ready to practice multiplying one- and two-digit numbers in the Got It? section.