Singapore Math Drills Team · 30 October 2026
Free, distraction-free math drills aligned to the MOE syllabus. No sign-up needed to try.
A little corner shop opens under a striped awning. On the shelf sit a kite, a ball and a toy boat, each with a price tag. "Welcome to the Coin Shop! What can your coins buy?"
That is Coin Shop, a 30-second Primary 2 episode of our Topic Explainers series. It is made for your child to watch, with simple words on screen and no voice-over. Watch it together first, then read on.
The episode makes four stops. Five coins are counted for the kite, and the price comes to 3 dollars 40 cents. That price is then written two ways, $3.40 and 340 cents. The ball's tag says 275 cents and the boat's says $6.80, and each is rewritten the other way. Last, the three toys line up from the cheapest to the most expensive.
These are the Primary 2 money skills in the MOE syllabus: counting money in dollars and cents, reading and writing money in decimal notation, converting between decimal notation and cents, and comparing two or three amounts. Adding and subtracting money in decimal notation comes in Primary 3, so this post stays with counting, writing and comparing.
In Primary 1, your child counted cents up to one dollar and dollars up to 100 dollars, but never both at once. Primary 2 brings them together, and one fact holds it all up: 1 dollar is 100 cents.
Reading decimal notation. In $3.40, the number before the dot is the dollars and the two digits after the dot are the cents. So $3.40 is read as "three dollars and forty cents". There are always two digits after the dot, because cents go up to 99.
Dollars to cents. Turn the dollars into cents (each dollar is 100 cents), then add the cents. $3.40 is 300 cents and 40 cents, which is 340 cents.
Cents to dollars. Take out every whole 100 cents as a dollar, and the cents left over go after the dot. 275 cents is 200 cents (2 dollars) and 75 cents, which is $2.75.
Comparing. Write every amount the same way first, then compare the dollars. If the dollars are the same, compare the cents.
Five coins drop into the tray: three one-dollar coins and two 20-cent coins. How much is that?
Step 1: Count the dollars first. Count on: $1.00, $2.00, $3.00.
Step 2: Count on with the cents. The first 20-cent coin makes $3.20, and the second makes $3.40.
| Coin | Total so far |
|---|---|
| 1 dollar | $1.00 |
| 1 dollar | $2.00 |
| 1 dollar | $3.00 |
| 20 cents | $3.20 |
| 20 cents | $3.40 |
Step 3: Say it in words. The kite costs 3 dollars and 40 cents, written $3.40.
Counting the dollar coins first keeps the steps tidy: the dollars before the dot are settled, and only the cents change at the end.
The kite's tag says $3.40. Write it in cents.
Step 1: Split the price. $3.40 is 3 dollars and 40 cents.
Step 2: Change the dollars to cents. Each dollar is 100 cents, so 3 dollars is 300 cents.
Step 3: Add the cents. 300 + 40 = 340. So $3.40 is 340 cents.
Now the other way round. The ball's tag says 275 cents. Write it in dollars and cents.
Step 1: Find the whole dollars. 275 cents has 2 hundreds, so it holds 200 cents, which is 2 dollars.
Step 2: Find the cents left over. 275 − 200 = 75, so 75 cents are left.
Step 3: Write it with the dot. 2 dollars and 75 cents is $2.75.
And one more, from the boat: $6.80 is 6 dollars (600 cents) and 80 cents, so $6.80 is 680 cents.
A helpful pattern to point out: in all three, the digits stay the same and in the same order. $3.40 and 340 cents both use 3, 4, 0. Only the dot and the unit change. Your child can use this as a check whenever the price is at least one dollar and has two digits after the dot.
The kite costs $3.40, the ball costs 275 cents and the boat costs $6.80. Which toy costs the most, and which costs the least?
Step 1: Write every price the same way. The ball is 275 cents, which is $2.75. Now all three are in dollars and cents: $3.40, $2.75 and $6.80.
Step 2: Compare the dollars. 6 dollars is the most, so the boat costs the most. 2 dollars is the least, so the ball costs the least.
Step 3: Put them in order. From least to most: ball $2.75, kite $3.40, boat $6.80.
Step 4: Check in cents. 275 cents, 340 cents, 680 cents. The order is the same.
Step 1 is the important one. Without it, "275" looks like the biggest number on the shelf, even though the ball is the cheapest toy.
$3.40, not $3.4. And three dollars and five cents is $3.05, not $3.5. Remind your child that cents always take two places after the dot.$3.40 as 40 cents, or 275 cents as $75. Ask, "How many whole dollars are in this price?"$3.40 cents" or "340 dollars". A price uses either the dollar sign and the dot, or the word cents, never both.$4.5 for four dollars fifty, and ask your child to fix it.Keep each game short and let your child handle real coins wherever possible. Real coins come first, then pictures of money, then written prices: the concrete, pictorial, abstract order of Singapore math teaching. For a look at how a P2 paper is shaped, Primary 2 sample questions explained walks through several question types, and if your younger child is just starting with money, our post on counting coins and number sense covers the P1 foundations.
Money is a topic children use every day, which makes it a wonderful one to practise little and often. A few minutes reading prices together does more than a long worksheet once a week.
That is how we built Singapore Math Drills. Practice is calm by design: no guilt-tripping over a missed day and no dark patterns, and your child's progress is only ever measured against their own. Our free sample has real practice questions for every Primary level, with no login and no download. Count the coins. Read the price!
Try a free interactive worksheet and see how calm practice feels, with no signup or credit card required.