__Objectives__

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 **smallest** to 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. E**xample: 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.

717.822 ÷ 1.26 = 717.822 × 100 ÷ 1.26 × 100

=71782.2 ÷ 126

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