Topics · Primary Maths · Money
Money: dollars, cents, and writing them properly
Money is decimals with a fixed number of places and a dollar sign in front. The sums are rarely hard; the marks go on writing the answer in the form the question asked for.
- 589 exam papers analysed
- appears in 99% of P6 Maths papers
- ~3 min read
01 Two units, one number
100 cents make 1 dollar. So $1.50 and 150¢ are the same amount written two ways, and a question may want either.
The dot is a decimal point, not a divider between two separate numbers. In $4.05 the digits after the point are cents: zero tens of cents and five cents, which is five cents — not fifty.
This is why money always shows two figures after the point. $1.5 is not wrong arithmetic, it is an incomplete way of writing $1.50, and papers mark it as such.
02 Converting between them
Both directions are just a shift of two places, because there are 100 cents in a dollar.
- Cents to dollars: divide by 100. 350¢ → $3.50. Two places right, and put the dollar sign on.
- Dollars to cents: multiply by 100. $2.05 → 205¢. Drop the sign and the point.
- Mixed amounts: 3 dollars and 5 cents is $3.05, not $3.5. The cents always take two columns, so a single-digit number of cents needs a nought in front.
- Adding a nought is not adding value. $3.5 written properly is $3.50 — the nought fills the cents column and changes nothing.
03 Adding, subtracting and giving change
Line the decimal points up and the columns do the rest — cents under cents, dollars under dollars. That single habit prevents most of the errors on this topic.
Change is a subtraction: what you gave minus what it cost. It is worth checking by adding back — if the change plus the price does not come to what you handed over, something is wrong.
04 Money in word problems
From P4 onwards money is mostly a costume worn by other topics — ratio, fractions, percentage and multi-step word problems all turn up wearing dollar signs.
Treat the dollars as ordinary numbers while you work, and put the notation back at the end. The one thing to hold on to is what the question actually asked for: how much did he spend, how much has he left, and how much more did A spend than B are three different answers from the same model.
05 How to say them
These are words most children have never said out loud, and a word you cannot say is a word you avoid using. Capitals mark the syllable you lean on. Tap the speaker to hear it.
- cent, written ¢saysentmore than onecents
The small unit of Singapore money. 100 cents make one dollar.
- dollar, written $sayDOL-uhmore than onedollars
The main unit of Singapore money, worth 100 cents.
- decimal pointmore than onedecimal points
The dot in $4.05. Everything after it is cents, and money always writes two figures there.
- changemore than one—
The money given back when you pay more than something costs. What you gave minus what it cost.
- totalsayTOH-tuhlmore than onetotals
Everything added together — the whole bill rather than one item.
06 What each level is tested on
The same topic, asked differently as it goes up. The percentage is the share of papers at that level in which it appears.
- P2
Recognising notes and coins, and counting a small amount of money.
Practise P2 Money — 10 questions →83% of P2 papers
- P3
Writing amounts in dollars and cents, converting between them, and simple change.
Practise P3 Money — 23 questions →90% of P3 papers
- P4
Adding and subtracting money in column form, and two-step shopping problems.
Practise P4 Money — 10 questions →95% of P4 papers
- P5
Money inside fraction and percentage problems — discounts, and a fraction of an amount spent.
Practise P5 Money — 10 questions →93% of P5 papers
- P6
Multi-step problems where money is the quantity in a ratio or a before-and-after model.
Practise P6 Money — 10 questions →99% of P6 papers
07 Mistakes worth knowing about
Each of these is wrong. Decide why before you open it.
“The answer is $1.5.”
Money takes two figures after the point: $1.50. Papers treat the missing nought as a wrong answer, not as a shortcut.
“$4.05 is four dollars and fifty cents.”
Five cents. The first column after the point is tens of cents, so $4.05 is 4 dollars, 0 tens of cents and 5 cents. Four dollars fifty is $4.50.
“350 cents is $35.”
$3.50. Dividing by 100 moves two places, not one.
“I added $2.40 and 60¢ and got $2.100.”
Convert to the same unit first. 60¢ is $0.60, and $2.40 + $0.60 = $3.00. Cents do not carry at ten.
“The question said how much change, and I wrote the price.”
Read the last sentence again before writing. Spent, left, change and difference are four different answers from the same working.
Now try it
63 questions across 5 levels, marked as you go with the working shown.