Mathematics notes, unit 4

Money

Textbook Mathematics Year 2 (DLP), Part 1 and Part 2 (one combined PDF), pages Part 2, 19–38

What this chapter covers

You can recognise Malaysian notes and coins and say their value (4.1.1)
You can read and write the value of money up to RM100, with ringgit and sen (4.1.2)
You can add money up to RM100 and solve simple problems (4.2.1, 4.2.2)
You can subtract money, find the difference and find the balance (4.3.1, 4.3.2)
You can multiply money by 2, 3, 4, 5, 6, 7, 8, 9 and 10 (4.4.1)
You can divide money equally by 2, 3, 4, 5, 6, 7, 8, 9 and 10 (4.5.1)
You can plan to save and spend money wisely (4.6.1)
You can solve money problems (4.7.1)

4.1Recognise money and its value

We use ringgit (RM) and sen to buy things. Money comes as notes and coins.

Six notes: RM1, RM5, RM10, RM20, RM50 and RM100 — Notes: RM1, RM5, RM10, RM20, RM50 and RM100.

Four coins: 5 sen, 10 sen, 20 sen and 50 sen — Coins: 5 sen, 10 sen, 20 sen and 50 sen.

Front and back of RM20, RM50 and RM100 notes, showing the value, a hibiscus flower and a picture on the back — The RM20, RM50 and RM100 notes (front and back). Each note shows its value and a hibiscus flower.

Based on the Year 2 textbook, Part 2, page 20.

RM1 = 100 sen. A decimal point separates the ringgit from the sen. In RM20.90, the 20 is ringgit and the 90 is sen.

Money	Say it	Write it
RM50	fifty ringgit	RM50
RM20.90	twenty ringgit and ninety sen	RM20.90
RM37.50	thirty-seven ringgit and fifty sen	RM37.50
5 sen	five sen	RM0.05
80 sen	eighty sen	RM0.80

Always write two digits after the decimal point. 5 sen is RM0.05, not RM0.5. RM0.5 would mean 50 sen.

Different ways to make the same amount

One RM20 note, one RM5 note, one RM1 note, one 50 sen coin and one 20 sen coin — RM20 + RM5 + RM1 + 50 sen + 20 sen = RM26.70.

Worked example: find the value

Step 1. Add the notes first: RM20 + RM5 + RM1 = RM26.
Step 2. Add the coins: 50 sen + 20 sen = 70 sen.
Step 3. Put them together: RM26.70.

What is the value of one RM10 note, two RM1 notes and one 50 sen coin?

Show answerHide answer

RM10 + RM2 = RM12, and 50 sen is RM0.50. The value is RM12.50.

4.2Adding money

We add money the way we add numbers. Keep the decimal points in a straight line, then add the sen first and the ringgit next.

Worked example: RM68.10 + 80 sen

Step 1. Write 80 sen as RM0.80.
Step 2. Line up the decimal points:

	RM68.10
+	RM0.80
	RM68.90

The total price is RM68.90.

Worked example: RM24.80 + RM56.70

Step 1. Sen: 80 + 70 = 150 sen. 150 sen is RM1.50, so write 50 sen and carry RM1 to the ringgit.
Step 2. Ringgit: 24 + 56 + 1 = 81.
The total is RM81.50.

Whole ringgit can be written with .00. RM30 is the same as RM30.00. This helps you line up the numbers.

Do not forget to carry. 100 sen is RM1. If the sen add up to 100 or more, carry 1 to the ringgit column.

RM20 + RM70 = ? and RM51.30 + RM18.25 = ?

Show answerHide answer

RM20 + RM70 = RM90. RM51.30 + RM18.25 = RM69.55.

4.3Subtracting money

The difference is how much more one price is than another. The balance is the money you have left after paying.

Worked example: RM90 − RM20

RM90 − RM20 = RM70. The price difference is RM70.

Worked example: RM74.80 − RM20.50

Step 1. Sen: 80 − 50 = 30 sen.
Step 2. Ringgit: 74 − 20 = 54.
The answer is RM54.30.

Worked example: regrouping, RM30 − RM25.70

Step 1. Write RM30 as RM30.00. You cannot take 70 sen from 0 sen.
Step 2. Take RM1 from the ringgit. RM1 = 100 sen. Now RM29 and 100 sen.
Step 3. 100 − 70 = 30 sen. 29 − 25 = 4 ringgit.
The balance is RM4.30.

Worked example: Siti pays RM100 for two toys, RM19.90 and RM57.50

Step 1. Subtract the first price: RM100 − RM19.90 = RM80.10.
Step 2. Subtract the second price: RM80.10 − RM57.50 = RM22.60.
Siti's balance is RM22.60.

Check by adding. RM54.30 + RM20.50 = RM74.80. If you get back the money you started with, your answer is right.

Always take the smaller amount from the larger amount. RM25.70 − RM30 is not possible.

Ali has RM50. He buys a ruler for RM3.40. What is his balance?

Show answerHide answer

RM50 − RM3.40 = RM46.60.

4.4Multiplying money

Multiplying is the same as adding the same amount again and again.

Worked example: 3 packets of jackfruit at RM8 each

Repeated addition: RM8 + RM8 + RM8 = RM24.
Multiplication: 3 × RM8 = RM24.

Worked example: 4 × RM5 and 10 × RM9

4 × RM5 = RM5 + RM5 + RM5 + RM5 = RM20.
10 × RM9 = RM90 (use the 10 times table).

Use your times tables. 6 × 10 = 60, so 6 × RM10 = RM60.

What is the price of 5 pens at RM4 each?

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5 × RM4 = RM20.

4.5Dividing money

Dividing money means sharing it equally.

Worked example: RM15 shared equally among 3 persons

RM15 ÷ 3 = RM5. Each person gets RM5.
Check: 3 × RM5 = RM15.

Worked example: 7 kg of durians cost RM63

RM63 ÷ 7 = RM9. The price of 1 kg is RM9. (Think: 7 × 9 = 63.)

Division is the opposite of multiplication. To find RM72 ÷ 9, ask "9 times what is 72?" The answer is 8, so RM72 ÷ 9 = RM8.

RM48 is shared equally among 6 children. How much does each child get?

Show answerHide answer

RM48 ÷ 6 = RM8.

4.6Money literacy and solving problems

Zarif won RM300. He plans to save RM200 in the bank, spend RM50 on books, RM40 on toys and give RM10 to the orphans' fund. Good planning means we save some money, spend wisely and help others.

Solve a money problem in four steps

Step 1. Read and underline the important numbers.
Step 2. Plan: decide whether to add, subtract, multiply or divide.
Step 3. Solve and write the number sentence.
Step 4. Check using the opposite operation.

Worked example: Ana has RM90

She buys a cake for RM54.60 and a gift for RM27.
RM90 − RM54.60 − RM27 = RM8.40.
Check: RM54.60 + RM27 + RM8.40 = RM90. Correct!

Summary

RM1 = 100 sen. The decimal point separates ringgit from sen. 5 sen is RM0.05.
Notes: RM1, RM5, RM10, RM20, RM50, RM100. Coins: 5, 10, 20 and 50 sen.
Add and subtract with the decimal points in line. 100 sen is regrouped to or from RM1.
Difference = how much more. Balance = money left.
Multiply by repeated addition or times tables. Divide to share equally.
Solve problems: read, plan, solve, check.