Measuring, Time and Money
Primary 2 · Mathematics
Measuring, Time and Money
Lesson 3 of 3
13 min
Let's begin
Ishimwe walks to the little shop near the school. In his hand is one shiny 100 Frw coin.
He wants a mandazi and a small banana. Is his money enough?
And if he pays, how much should the shopkeeper give back? Today you become the boss of your money.
In Rwanda we buy things with francs. We write it short: Frw.
These are the coins you will see in your hand:
1 Frw, 5 Frw, 10 Frw, 20 Frw, 50 Frw, 100 Frw.
The number on the coin tells you how much it is worth. A 100 Frw coin is worth more than five 10 Frw coins. Bigger number, more value.
For a lot of money we use paper notes, like 500 Frw and 1000 Frw. Today we stay with coins up to 100 Frw.
Start with the biggest coin. Then add the smaller ones.
Worked example
Keza has one 50 Frw coin, one 20 Frw coin and one 10 Frw coin.
Start big: 50.
Add 20: 50 and 20 make 70.
Add 10: 70 and 10 make 80.
Keza has 80 Frw.
Worked example
Gatete has three 10 Frw coins and one 5 Frw coin.
Three tens make 30. Then 30 and 5 make 35 Frw.
Remember: count the value, not the number of coins. Gatete has 4 coins, but 35 Frw!
At the shop, put the prices together to find the total.
Worked example
A pencil costs 40 Frw. A rubber costs 30 Frw.
40 and 30 make 70 Frw in total.
Worked example
Ishimwe wants a mandazi for 60 Frw and a banana for 30 Frw.
60 and 30 make 90 Frw.
He has 100 Frw. 90 is less than 100, so yes, he has enough.
You often pay with more money than the price. The shopkeeper gives back the rest. That is your change.
The easy way: count up from the price to the money you paid.
Worked example
Ishimwe pays 100 Frw. His things cost 90 Frw.
Count up from 90 to 100. That is 10.
His change is 10 Frw.
Worked example
Mutesi buys a sweet for 70 Frw. She pays with 100 Frw.
Count up: 70, then 80, then 90, then 100. That is three tens, so 30.
Her change is 30 Frw.
Worked example
Habimana buys chalk for 45 Frw. He pays with a 50 Frw coin.
Count up from 45 to 50. That is 5.
His change is 5 Frw.
Worked example
Umutoni buys a pen for 45 Frw and a rubber for 25 Frw. She pays 100 Frw.
Step 1 — add the prices. 45 and 25 make 70 Frw.
Step 2 — count up from 70 to 100. That is 30.
Her change is 30 Frw. Always add first, then find the change.
Worked example
A small book costs 75 Frw. Byiringiro has only 60 Frw.
60 is less than 75. He does not have enough.
How much more does he need? Count up from 60 to 75. That is 15.
He needs 15 Frw more. Tomorrow he will bring it!
Tip
Change means count up
Start at the price. Climb up to the money you paid. The steps you climbed are your change.
Your change is always smaller than the money you handed over. If your answer is bigger, you added instead of counting up. Try again!
Work them out on paper, then tap Show answer to check.
What you learned today
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