lesson
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Imagine you are at the school book fair with a five-dollar bill in your pocket. You pick out a bookmark for \1.35andafungelpenfor$2.40$.
To know if you have enough money at checkout, you need to combine both prices into one total.
Before we add them up, let's look at the two different ways we write money.
Cents and Dollars
We can write prices using cent notation with a cent sign (Β’), or decimal notation with a dollar sign (\) and a dot.
The decimal point is a dot that separates whole dollars on the left from cents on the right.
πA clean visual diagram comparing cent notation and decimal notation. Top card shows 'Cent Notation: 245Β’'. Bottom card shows 'Decimal Notation: $2.45'. An arrow points to the decimal point with a label 'Decimal Point separates dollars and cents'. A callout box on the right shows '100Β’ = $1.00' with 100 small 1Β’ coins equal to one $1 bill. High contrast colors, dark blue #1e2945 text, subtle borders.
Since 100Β’ makes one whole dollar, what happens when we add prices written entirely in cents?
Adding with Cent Notation
Adding cents works just like standard addition with whole numbers.
Suppose an eraser costs 65Β’ and a sticker costs 58Β’. We line them up by place value and add: 65Β’+58Β’=123Β’.
πA vertical math addition card showing '65Β’ + 58Β’ = 123Β’'. Show column alignment: ones column (5 + 8 = 13, show carry 1 over the tens), tens column (1 + 6 + 5 = 12). Below the sum of 123Β’, show an arrow converting 123Β’ into $1.23 because 100Β’ equals 1 dollar.
Cent notation is straightforward, but most store price tags use dollar signs and dots. How do we add those?