# MULTIPLICATION OF DECIMALS

LESSON PLANNING OF MULTIPLICATION OF DECIMALS

Subject Mathematics

Students` Learning Outcomes

• Multiply a decimal by tenths and hundredths only.
• Multiply a decimal by a decimal (with three decimal places)
• Multiply a decimal by a decimal (in the same way as for whole numbers and then put in the decimal point accordingly)

Information for Teachers o   Multiply simply by ignoring the decimal points.

o   Then put the decimal point in the answer-it will have as many decimal places as the two original numbers combined. Count and add the decimal places of both numbers and put the decimal point in the product as per counting.

o   For example:  Calculate 3.24  0.6

o   Thus, 3.24 0.67 = 2.1708.

o   There are 2 decimal places in 3.24 and 2 decimal places in 0.67 and thus, so answer will be 4 decimal places.

o   If addition of decimal places of both number is 4. And the product is of three digits only, then put “0” to the left of the answer and place decimal point.

o   First ignore the decimal points and simply multiply 324 by 67. Then include the 4 decimal places in the answer.

o   Consult textbook when and where required.

Material / Resources

Writing board, chalk / marker, duster, textbook

Introduction

• Revise the place value for decimals for tenths, hundredths, and thousandths.
• Write the word name for a decimal and vice versa.

• Arrange decimals to the thousandths. For example write 4.567, 0.999, and 4.699
• Write the decimal equivalent of a fraction with a denominator of 1,000.

Development

Activity 1

• Tell the students that if we multiply any decimal number with tenths 1 / 10 then move the decimal point one digit to the left of the given number e.g.

• Similarly if we multiply decimal number with hundredth 1 / 100 or 1/1000. We move the decimal point after two digits and three digits to the left side of decimal number respectively.
• Give some question for practice to students in which multiplication of decimal numbers with, 1/10, 1/100, 1/1000 and is given.

Activity 2

• Ask the students can you solve 2.132 x 14. [Collect answer and ask how they did it]

• Illustrate an example on board.
• Multiply 0.03 by 1.1.
• Multiply without decimal points:
• 3 x 11 = 33
• 0.03 has 2 decimal places, and 1.1 has 1 decimal place. So the answer will be 3 decimal places i.e. 0.033.
• Do two or three more questions on board for practice.

Activity 3

• Split the class into groups.
• Assign questions with time limit.

• Invite one person from each group to attempt question on the board.
• Split the class into pairs, give some exercise questions.
• Move around and observe pair work.
• Help the slow learner.

Sum up / Conclusion

• Repeat that the answer should have the same number of decimal places as are in both the numbers you are multiplying.
• If the total of both the number is 3 and there are 2 digits in the answer then add zero on the left before placing the decimal point.

Assessment

• Give few questions to check students learning. For example;

• Fill in the boxes in the following questions: