Dividing decimals
🎯 In this topic you will
- Estimate and divide numbers with 1 or 2 decimal places by a one-digit whole number.
- Estimate and divide numbers with 1 or 2 decimal places by a two-digit whole number.
🧠 Key Words
- dividend
- divisor
- quotient
Show Definitions
- dividend: The number that is being divided in a division calculation.
- divisor: The number by which the dividend is divided.
- quotient: The result obtained after dividing one number by another.
🍊 Comparing Prices per Orange
Mandisa wants to know which pack of oranges is the better deal. Pack A contains four oranges for $2.50, while Pack B contains three oranges for $1.89. To decide which pack is cheaper, she needs to compare the cost of a single orange in each pack.
🧮 Dividing the Cost
To find the cost of one orange, Mandisa must divide the total price by the number of oranges in the pack. This method helps compare the price per item and decide which pack offers better value. In this section, you will learn how to divide decimal numbers by whole numbers so you can solve problems like this.
💡 Quick Math Tip
Find the cost per item: To compare two deals, divide the total price by the number of items in each pack. The smaller result shows the cheaper option per item.
❓ EXERCISES
1. Calculate.
a. $37.2 \div 4$
b. $3.2 \div 8$
c. $0.36 \div 4$
d. $140.05 \div 5$
Check your answers with your partner.
👀 Show answer
b. $3.2 \div 8 = 0.4$
c. $0.36 \div 4 = 0.09$
d. $140.05 \div 5 = 28.01$
2. Calculate.
a. $36.84 \div 12$
b. $75.75 \div 15$
Check your answers with your partner.
👀 Show answer
b. $75.75 \div 15 = 5.05$
3. Find the missing digit.
👀 Show answer
4. Ahmed is thinking of a number.
He multiplies his number by $14$ and the answer is $86.8$.
What number is Ahmed thinking of?
👀 Show answer
Ahmed's number is $6.2$.
5. Find the odd one out.
$7.75 \div 5 \quad 9.3 \div 6 \quad 12.32 \div 8 \quad 13.95 \div 9$
Explain your answer.
👀 Show answer
$9.3 \div 6 = 1.55$
$12.32 \div 8 = 1.54$
$13.95 \div 9 = 1.55$
The odd one out is $12.32 \div 8$ because it equals $1.54$ while the others equal $1.55$.
6. Ella, Kiki and Mandy spend $29.52$ on food.
They share the cost equally between them.
How much does Mandy pay?
👀 Show answer
Mandy pays $9.84$.
7. Two shops sell paint.
Shop A sells $4$ pots of paint for $6.88$.
Shop B sells $3$ pots of paint for $5.22$.
Which shop has the better deal? Explain your answer.
👀 Show answer
Shop B: $5.22 \div 3 = 1.74$ per pot.
Shop A is the better deal.
8. A regular pentagon is drawn on the playground.
The perimeter of the pentagon is $26.25$ metres.
What is the length of one side of the pentagon?
👀 Show answer
$26.25 \div 5 = 5.25$ metres.
Each side is $5.25$ metres long.
🧠 Think like a Mathematician
Challenge: Use each of the digits 2, 3, 4, 5 and 6 exactly once to complete the calculation.
$329.68 \div \square\square = \square.\square$
Think about it:
- Estimate the division first to see which two-digit number is close to $50$.
- Use the digits given to build a reasonable divisor and quotient.
- Check that the digits $2,3,4,5,6$ are each used exactly once.
👀 show answer
- A correct completion is: $329.68 \div 56 = 5.89$.
- The digits used are 5 and 6 for the divisor, and 5, 8, and 9 appear in the quotient, which fits the estimate that the answer should be a little below $6$.