Multiplying By Multiples of 10

Read the lesson below on multiplying by multiples of 10 and then work through it with your child. Print off the worksheets before starting.

Introduction/ Warm-up

Students normally learn best when they can associate what they are learning with what they already know. This introduction will provide your child with an opportunity to do this and help prepare them for what is to be learned later in this lesson.

This introduction should take around 10-15 minutes. Do not worry if it takes longer.

Materials Needed: Cut out the flashcards from the two sets below:

• Products to 45 e.g. 6 x 4
• Products to 81 e.g. 8 x 7

Steps

1. Play the game “What’s my fact?” to review multiplication facts with your child. This will help them recall prior knowledge before getting into the lesson content.
2. To play Memory with your child, place the flashcards on the table facedown.
3. Instruct your child to turn over one multiplication card at a time and solve the problem. If they get the problem right they get to keep the card, if the answer is incorrect they put the card back.
4. Alternate turns between your children. If you are playing with one child then play the game too. However, have them solve the problem on your turn as well. If they get the problem wrong then, you keep the card. If they get the problem right then they keep the card.
5. The object of the game is to have the most cards at the end of the game.
6. As you play the game evaluate how well your child answers the multiplication problems. This is designed to give you an idea of how well they know their multiplication facts before learning more complex concepts in multiplication. If they struggle with basic multiplication facts you may want to review those facts prior to moving forward.

Lesson Explanation

This part should take around 20 to 30 minutes but you can take as long as necessary.

Step 1:
Review the above standard that this lesson is based on to help your child see what they will be learning and why.

• Explain that they will be learning more about multiplication.
• Let your child know that what was practiced in the warm-up was a great start but that they will be learning ways to complete harder multiplication problems

Step 2:
Tell your child that you will show him how to multiply one-digit whole numbers by multiples of 10.

• Discuss with them that when they multiply basic facts, like the facts that were used in the game, they are drawing on their own memorization skills.
• Let them know that when they multiply numbers with more than one digit they have to use these same skills to solve the problem.
• Ask your child to write the following problem on a sheet of paper. 3 x 20.
• When this is complete have them show you how they wrote the problem. Then complete the steps below to show them how to write the problem according to proper place value principles and how to solve the problem.

1. Tell your child that when they write a problem with more than two-digits in the number they must line up the numbers so they are in the right place value columns.
2. Demonstrate to them on a board or on a sheet of paper how to write the multiplication problem shown below.
   2 0
   x 3
3. Explain that when the write a multiplication problem with a number that has more than two-digits they must put the larger number on top and then line it up according to place value. As in this example, the 3 must be underneath the 0 because they are both in the ones place. The 2 in 20 is in the tens column.
4. Now show your child how to solve the problem. Explain that when they solve the problem the only need to look at the each set of numbers one at time.  They will solve the problem from right to left starting with the lowest place value column, which in this case is the ones column.
5. To solve the problem in this column they must multiply 0 x 3, which equals 0. See below.
   2 0
   x 3
6. Once the ones column has been multiplied, tell your child that you will now multiply the tens column. See below.
   2 0
   x 3
   6 0
7. Explain to your child that when you write your answer the numbers must be lined up according to place value column they multiplied it from. So in this example they must place the 6 underneath the tens column and the 0 in the ones column.
8. Once they do this the have solved the problem and in this case they now know that 20 x 3 = 60.

Step 3:

• Explain to your child that they have learned one method for solving multiplication problems with one and two-digits and now they can learn a shortcut to more quickly solve problems that have multiples of ten.
• Tell your child that to do this they must rely on their knowledge of basic multiplication facts.
• Work through the following

1. Write the following problem on the board or on a sheet of paper.
   4 0
   x 2
2. Explain to your child that when they see any two-digit number that has a zero in it, that they can easily multiply the problem.
3. Tell them that what they do is simply cover up the 0 or pretend it is not there and bring the zero down as shown below. They will then multiply the other number. For example in the problem above they will multiply 4 x 2.
   4 0
   x 2
   0
4. Now ask your child to tell you what 4 x 2 is and then write the answer on the board next to the zero.
5. Tell your child that they have just solved the problem and the answer is 80. So anytime they see a problem that is a multiple of ten or has a zero in it they bring the zero(s) down and then multiply the other numbers to get the answer.
6. Complete this concept again with 50 x 7. Walk them through steps 3 and 4.
7. Discuss with your child another way to think of 40 x 2; 40 can be thought of as 4 tens. 2 times 4 tens is 8 tens. 8 tens is 80

Guided Practice

Step 4:

• Together complete worksheet #1 using the traditional method on half of the problems and the shortcut method on the other half. Work through each type of problem with your child to help them master concepts from the lesson.
• If you are working with more than one child then group them together to complete Worksheet #1.
• If you are working one-on-one with your child alternate turns completing problems on worksheet #1. However, make sure to let them ‘help’ you solve your problems to keep them involved in the learning.
• Review concepts that they may not completely understand or have questions with.

Independent Practice/ Lesson Closure

• Play bingo with your child to help them master the concepts taught individually. If you are completing the lesson with only one child play bingo with them.
• To play you will need to use multiplication bingo worksheet #2.
  1. Give each player a bingo card.
  2. Call out the various problems listed on multiplication bingo worksheet #2.
  3. If a problem is called on your child’s card then they are to solve the problem using their preferred method.
  4. The first person to have a card that is completely blacked out with correct answers wins!

Lesson Variations

• Children who struggle with this lesson may benefit from reviewing basic multiplication facts. They may also benefit from reviewing place value concepts.
• Children who excel with this lesson are ready from more complicated multiplication problems.
• If your child is advanced have him/her help you with solving the examples on the board to keep them engaged with the lesson.
• If your child is struggling, have them help with reading the problems, working out components to the problem that they excel in to keep them engaged.
  • You may also consider giving your child a worksheet on simple multiplication facts if they are significantly struggling with the materials.

Multiplying by Multiples of 10 Worksheets

The 2 worksheets listed above are grouped below:

• Multiplying by Multiples of 10 (e.g. 50 x 7)
• Multiplication Bingo (with multiplication by multiples of 10)