At the end of this lesson, students should be able to:
Order numbers in ascending or descending order.
Add and subtract whole numbers and decimal numbers.
Multiply and divide whole numbers and decimal numbers.
Ordering Numbers
Ordering numbers means to organize numbers in a particular pattern, ascending or descending.
Ascending order
Numbers are in ascending order when they are arranged from the smallestto the largest number. Example: 157, 324, 879, 999, 1055
Descending order
Numbers are in descending order when they are arranged from the largest to the smallest number. Example: 391, 245, 167, 38.
Example 1
Write these measures in descending order; 2m, 60cm, 800mm, 180cm, 0.75m
Solution
First change all the measurements into the same unit.
The solution to the question becomes 2 m, 180 cm, 800 mm, 0.75 m and 60 cm in descending order.
Adding Whole Numbers and Decimal Numbers
Example 1:21376 + 15 + 2 + 96498.
Note: Arrange the numbers vertically and add. (Make sure the digits are aligned in their correct place value.)
Solution:
Example 2:144 + 2.18 +9007 + 16.345
Solution
Subtracting Whole Numbers and Decimal Numbers
Example 1:91234 – 698
Note: Arrange the numbers vertically and subtract. (Make sure the digits are aligned in their correct place value.)
Solution
Example 2: 5368 – 8.329
Solution
Multiplying Whole Numbers and Decimal Numbers
Example 1:846 × 79
Solution
Example 2:237.5 × 4.36
Solution
Dividing Whole Numbers and Decimal Numbers
Example 1:56232÷9
Solution
Example 2
109.94 ÷ 23
Solution
Example 3:717.822 ÷ 1.26
Solution
Note: When the divisor is a decimal number, first you have to multiply the divisor and the dividend by a multiple of 10 which will make the divisor a whole number. If the divisor has 1 decimal place, multiply both numbers by 10. If it has 2 decimal places, multiply them by 100 and if it has 3 decimal places, multiply them by 1000. In this example, since the divisor has 2 decimal places, multiply them by 100 before you divide. As long as you multiply both numbers by the same number, you have not changed the question.