Primary 3 · Measurement & Geometry

P3 money

In P3, your child adds and subtracts money written in dollars and cents, such as $3.60 + $2.75. The marks are won or lost in the cents: every 100 cents must become $1.

Taught in
Term 1
Syllabus
1 skill
Usual slip
Cents not regrouped
Notes and coins making $6.35

What your child learns in P3 money

One skill, each with what it looks like on a worksheet.

Follows the latest (2026) MOE syllabus
See the syllabus wording
  • adding and subtracting money in decimal notation

Add and subtract money

Your child adds and subtracts amounts written in dollars and cents. 100 cents make $1, so cents that add up to 100 or more are regrouped into dollars.

GroupDetail
Book1×$2, 1×$1, 1×50c, 1×10c
Pen1×$2, 1×50c, 1×20c, 1×5c
A book and a pen

Words to know

Dollars
The part of an amount before the dot.
Cents
The part after the dot, always two digits. 100 cents make $1.
Regroup
Change 100 cents into $1, or change $1 into 100 cents.
Decimal notation
Writing money with a dot, such as $6.35.

The sentence that costs the mark

Mei buys a book for $3.60 and a pen for $2.75. How much does she spend?

What the working usually does

keep135¢=$5.135

Adds the dollars, 3 + 2 = 5, and the cents, 60 + 75 = 135, then writes the 135 straight after the dot.

What the question asked

regroup135¢=$6.35

Turns 100 of the 135 cents into $1 first, so the total is $5 + $1.35.

Both sums are right, and $5.135 even looks like a price. The only wrong step is where the 135 is written: cents have just two places, so 100 of them must move across as $1.

The same P3 money question, worked properly

Lah works through it the way she does every question in StudyLah: one step at a time, marking the picture as she goes.

Mei buys a book for $3.60 and a pen for $2.75. How much does she spend altogether?

Step 1 of 5▌
  1. Write the dollars and the cents in two columns. The dollars make $3 + $2 = $5.
  2. The cents make 60¢ + 75¢ = 135¢.
  3. 135¢ is more than 100¢, and 100¢ make $1. So 135¢ = $1.35.
  4. Now add the two amounts, $5 + $1.35 = $6.35.
  5. So Mei spends $6.35 altogether.

Every question in StudyLah comes with a walkthrough like this one.

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Three quick P3 money questions

Try them together, then tap to check.

Question 1

Add $4.80 and $1.45.

Show answer

Answer$6.25. The cents make 125¢, which is $1.25, so $5 + $1.25 = $6.25.

Question 2

Find $5.20 − $1.45.

Show answer

Answer$3.75. Change $1 into 100 cents first: 120¢ − 45¢ = 75¢, and $4 − $1 = $3.

Question 3

How do you write 2 dollars and 5 cents?

Show answer

Answer$2.05. Cents always take two digits, so 5 cents is written 05.

Helping at home

How to tell it has clicked

Give your child $3.60 + $2.75 and watch the cents. An answer with three digits after the dot, like $5.135, means the 100 cents were not changed into $1.

Try this tonight

Pay for two things at a shop counter with real coins. Count the cents first, and swap every 100 cents for a $1 coin before saying the total. That swap is the step this page is about.

Before and after P3 money

  1. Builds on

    Primary 2 Money

  2. You are here

    Primary 3 Money

    Adds and subtracts dollars and cents

More in Primary 3

See how your child is doing on this topic

StudyLah marks each step separately, so you can see whether it was the setup or the arithmetic that cost the mark.

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