Compare amounts of money

What you will learn

• Compare amounts of money

Models used: number sentences, stories, tables.

Before you start

• Write dollars and cents using decimal notation

Compare dollars first, then cents

Which amount is greater: $2.35 or $2.50?

1. Compare the same units. Read each value with the heading above its column.

   Both amounts contain two whole dollars. The dollar parts are equal, so they cannot decide which is greater.

   Different coins can have different values. One dollar and one hundred cents are two names for the same amount.

   Compare the same units

   Amount	Dollars	Cents
   $2.35	2	35
   $2.50	2	50

2. Both bars use the same scale. Compare their lengths and read the names beside them.

   Compare the cents next. Fifty cents is greater than thirty-five cents.

   35 < 50

   35 cents35

   50 cents50

   Difference: 15

3. Money uses two decimal places. Read each value with the heading above its column.

   The second amount has the same dollars and more cents, so $2.50 is greater. Writing $2.5 means the same as $2.50.

   $2.35 < $2.50

   Money uses two decimal places

   Smaller amount	Greater amount
   $2.35	$2.50

Worked example: A new example, together

Compare $6.18 □ $4.02.

1. Compare dollars first, then cents when the dollars match. Read each value with the heading above its column.

   Read every value and its unit. Keep dollars and cents distinct until you rename them.

   Using one common unit makes money values comparable and calculations consistent.

   Compare dollars first, then cents when the dollars match.

   First amount ($)	Second amount ($)
   6.18	4.02

2. Compare dollars first, then cents when the dollars match. Read each value with the heading above its column.

   Convert both amounts to cents.

   Compare dollars first, then cents when the dollars match.

   First amount ($)	Second amount ($)
   6.18	4.02

   Compare $6.18 □ $4.02.

   >

3. Compare dollars first, then cents when the dollars match. Read each value with the heading above its column.

   Convert both amounts to cents.

   Compare dollars first, then cents when the dollars match.

   First amount ($)	Second amount ($)
   6.18	4.02

4. Compare dollars first, then cents when the dollars match. Read each value with the heading above its column.

   Compare 618 and 402.

   Compare dollars first, then cents when the dollars match.

   First amount ($)	Second amount ($)
   6.18	4.02

5. Compare dollars first, then cents when the dollars match. Read each value with the heading above its column.

   Use >.

   Compare dollars first, then cents when the dollars match.

   First amount ($)	Second amount ($)
   6.18	4.02

6. Compare dollars first, then cents when the dollars match. Read each value with the heading above its column.

   Check the result against the question we started with.

   Compare the dollar amounts first, then any remaining cents.

   We found >. Using one common unit makes money values comparable and calculations consistent.

   Compare dollars first, then cents when the dollars match.

   First amount ($)	Second amount ($)
   6.18	4.02

Common mistakes to discuss

• More digits means more money. Compare dollars first, then cents. $6.18 is more than $4.02, and $0.60 is more than $0.55.

Check your understanding

• Compare amounts of money
• compare, combine or rename money while preserving its value
• check the answer against the original quantities and units

Explain your reasoning to an adult, then try a fresh question in the interactive lesson. A result from one attempt is not proof of lasting mastery.