What Are Some Solutions to Make Change: Counting Money and Calculating Differences

Learn how to make change using coins and bills: counting money, calculating differences, and problem-solving strategies.

Solution: Exercises 1 to 3
1 Counting coins to make change
Exercise 1
You buy a toy that costs 25¢. You pay with 50¢.
How much change should you get back?
Show different ways to make this change.
Definition:

Change: The money returned to you when you pay more than the cost of an item.

Solution method:
  1. Subtract the cost from the amount paid
  2. Find different combinations of coins that equal the change
  3. Count the total value of each coin combination
  4. Verify that each combination equals the correct amount
50¢
Paid
-
25¢
Cost
=
25¢
Change
Quarter
25¢
Dime
10¢
Nickel
5¢
Penny
1¢
Step 1: Calculate the change

Amount paid (50¢) - Cost (25¢) = 25¢ change

Step 2: Find coin combinations

One quarter = 25¢, or two dimes and one nickel = 20¢ + 5¢ = 25¢

Step 3: Verify the amounts

Quarter: 25¢ = 25¢, Dimes + Nickel: 10¢ + 10¢ + 5¢ = 25¢

Step 4: State the answer

You should get 25¢ back in change

Change = 25¢
Ways: 1 quarter OR 2 dimes + 1 nickel
Final answer:

You should get 25¢ back in change. This could be one quarter or two dimes and one nickel.

Applied rules:

• Subtraction: Amount paid minus cost equals change

• Coin values: Quarter = 25¢, Dime = 10¢, Nickel = 5¢, Penny = 1¢

• Equivalence: Different coin combinations can equal the same amount

2 Making change with dollars
Exercise 2
You buy a book that costs $3.75. You pay with $5.00.
How much change should you get back?
What bills and coins could make this change?
Definition:

Dollar notation: Money expressed in dollars and cents using the $ symbol and decimal point.

Dollars
$1, $5, $10
Coins
Quarter, Dime, Nickel, Penny
Total
$5.00 - $3.75
Step 1: Calculate the change

$5.00 - $3.75 = $1.25

Step 2: Break down the change

$1.25 = $1.00 + $0.25

Step 3: Find bill and coin combinations

One $1 bill + one quarter = $1.25

Step 4: Verify the amount

$1.00 + $0.25 = $1.25 ✓

Change = $1.25
One $1 bill + one quarter
Final answer:

You should get $1.25 back in change. This could be one $1 bill and one quarter.

Applied rules:

• Decimal subtraction: Subtract dollars and cents separately

• Bills and coins: Use the largest denominations first

• Verification: Check that your change adds up to the correct amount

3 Multiple solution paths
Exercise 3
You buy candy that costs 40¢. You pay with 75¢.
What are different ways to receive 35¢ in change?
Show at least 3 different combinations.
Definition:

Multiple solutions: Different combinations of coins that add up to the same total amount.

75¢
Paid
-
40¢
Cost
=
35¢
Change
Step 1: Calculate the change

75¢ - 40¢ = 35¢

Step 2: Find different combinations

Option 1: One quarter + one dime = 25¢ + 10¢ = 35¢

Step 3: Find more combinations

Option 2: Three dimes + one nickel = 30¢ + 5¢ = 35¢

Step 4: Find another combination

Option 3: Seven nickels = 7 × 5¢ = 35¢

Change = 35¢
Options: 1 quarter + 1 dime OR 3 dimes + 1 nickel OR 7 nickels
Final answer:

You should get 35¢ back in change. Possible combinations: one quarter + one dime, three dimes + one nickel, or seven nickels.

Applied rules:

• Multiple combinations: Same total can be made with different coins

• Systematic approach: Start with largest coins first

• Verification: Always check that each combination equals the target amount

Making Change Solutions
Change = Paid - Cost
Basic Formula
Quarter
25¢
Large coin
Dime
10¢
Medium coin
Nickel
5¢
Small coin
Penny
1¢
Tiny coin
Key definitions:

Change: The money returned when you pay more than the cost of an item

Coin: A small piece of metal money with a specific value

Bill: Paper money with a specific value

Value: How much money something is worth

Subtraction: Taking away one number from another

Making change methods:
  1. Calculate difference: Subtract cost from amount paid
  2. Identify coin values: Know the value of each coin
  3. Find combinations: Use different coins to make the same amount
  4. Verify total: Check that your coins add up to the correct change
  5. Optimize: Use the fewest coins possible when possible
Tip 1: Always subtract the smaller number from the larger number.
Tip 2: Start with the largest coins first to use fewer coins.
Tip 3: Count by tens (dimes) and fives (nickels) to make counting easier.
Tip 4: Always verify your change by adding it to the cost to check if it equals what you paid.
Common errors: Forgetting to subtract, counting coins incorrectly, not verifying totals.
Real-world applications: Shopping, paying for items, handling money transactions.
Essential rules:

• Change = Amount paid - Cost of item

• Quarter = 25¢, Dime = 10¢, Nickel = 5¢, Penny = 1¢

• Always verify your change calculation

• Use largest coins first when possible

Solution: Exercises 4 to 5
4 Real-world shopping scenario
Exercise 4
You buy school supplies that cost $2.30. You pay with $3.00.
How much change should you get back?
What are the different ways to make this change?
Definition:

Shopping scenario: A real-world situation involving buying items and receiving change.

$3.00
Paid
-
$2.30
Cost
=
$0.70
Change
Step 1: Calculate the change

$3.00 - $2.30 = $0.70

Step 2: Find different combinations

Option 1: Two quarters + two dimes = 50¢ + 20¢ = 70¢

Step 3: Find more combinations

Option 2: One quarter + four dimes + one nickel = 25¢ + 40¢ + 5¢ = 70¢

Step 4: Find another combination

Option 3: Seven dimes = 70¢

Change = $0.70
Options: 2 quarters + 2 dimes OR 1 quarter + 4 dimes + 1 nickel OR 7 dimes
Final answer:

You should get $0.70 back in change. Possible combinations include two quarters and two dimes, or seven dimes.

Applied rules:

• Real-world application: Connect math to everyday situations

• Multiple solutions: Same total can be made with different coins

• Verification: Always check that each combination equals the target amount

5 Problem-solving with constraints
Exercise 5
You buy a snack that costs 60¢. You pay with 85¢.
You want to receive the change using the fewest coins possible.
What is the best combination of coins?
Definition:

Optimization: Finding the best solution according to specific criteria (in this case, using the fewest coins).

85¢
Paid
-
60¢
Cost
=
25¢
Change
Step 1: Calculate the change

85¢ - 60¢ = 25¢

Step 2: Find the fewest coins option

One quarter = 25¢ (1 coin total)

Step 3: Compare with other options

Other options: Two dimes + one nickel (3 coins), Five nickels (5 coins)

Step 4: Choose the optimal solution

One quarter uses the fewest coins (1 coin vs 3 or 5 coins)

Best option: One quarter (fewest coins)
Final answer:

You should get 25¢ back in change. The best combination using the fewest coins is one quarter.

Applied rules:

• Optimization: Use largest coins first to minimize total coins

• Efficiency: Fewer coins is generally better

• Comparison: Evaluate multiple options to find the best one

Comprehensive Summary: Making Change Solutions
Change = Paid - Cost
Fundamental Formula
Coin Values
Quarter = 25¢
Coin Values
Dime = 10¢
Coin Values
Nickel = 5¢
Coin Values
Penny = 1¢
Complete definitions:

Change: The money returned to you when you pay more than the cost of an item. It's the difference between what you paid and what the item costs.

Coin: A small piece of metal money with a specific value. Common coins are quarters (25¢), dimes (10¢), nickels (5¢), and pennies (1¢).

Bill: Paper money with a specific value, such as $1, $5, $10, etc.

Subtraction: The mathematical operation of taking one number away from another. Used to calculate change: Paid - Cost = Change.

Multiple Solutions: Different combinations of coins that add up to the same total amount. For example, 25¢ can be one quarter or five nickels.

Optimization: Finding the best solution according to specific criteria, such as using the fewest coins possible.

Making change methods:
  1. Calculate the difference: Subtract the cost from the amount paid (Change = Paid - Cost)
  2. Identify coin values: Know the value of each coin (quarter = 25¢, dime = 10¢, etc.)
  3. Find combinations: Use different coins to make the same amount
  4. Verify totals: Check that your coins add up to the correct change
  5. Optimize: Use the fewest coins possible when possible
  6. Real-world application: Connect math to everyday shopping situations
Memorization trick: "Q-D-N-P" for Quarter-Dime-Nickel-Penny values: 25-10-5-1.
Counting method: Count by 25s for quarters, by 10s for dimes, by 5s for nickels.
Verification: Add your change back to the cost to make sure it equals what you paid.
Efficiency tip: Start with the largest coins first to use fewer coins overall.
Core concepts: Subtraction, coin values, multiple solutions, optimization, real-world application.
Application areas: Shopping, banking, budgeting, saving money, handling transactions.
Fundamental rules to memorize:

• Change formula: Change = Amount paid - Cost of item

• Coin values: Quarter = 25¢, Dime = 10¢, Nickel = 5¢, Penny = 1¢

• Subtraction: Always subtract the smaller number from the larger number

• Verification: Add change to cost to verify it equals amount paid

• Optimization: Use largest coins first to minimize total coins used

$1 = 100¢
25¢ + 25¢ = 50¢
10¢ + 10¢ + 10¢ = 30¢
Key Calculations

Questions & Answers

Question: I get confused when I have to make change. How can I remember which coins to use?

Answer: Here are helpful strategies to remember coin values:

  • Memory trick: Remember "Q-D-N-P" for Quarter-Dime-Nickel-Penny: 25-10-5-1
  • Practice with real coins: Handle actual coins to feel the differences
  • Count by values: Practice counting by 25s (quarters), 10s (dimes), 5s (nickels)
  • Start large: Always begin with the largest coins that fit into your change amount
  • Check your work: Add up your coins to make sure they equal the correct change

The more you practice, the more automatic it becomes!

Question: Sometimes there are many ways to make the same amount of change. How do I know which way is best?

Answer: When there are multiple ways to make change, here's how to choose:

  • Efficiency: Use the fewest coins possible (usually starting with largest coins)
  • Availability: Use coins you actually have available
  • Practicality: Consider what's easiest to handle and count
  • Standard practice: In stores, cashiers typically use the fewest coins

For example, 30¢ is best made with three dimes rather than thirty pennies!

Question: What if I subtract wrong and get the wrong amount of change? How can I check my work?

Answer: Here are effective ways to check your change calculations:

  • Addition check: Add your change to the cost - it should equal what you paid
  • Count up: Start with the cost and count up to what you paid
  • Estimation: Does your answer make sense? (Change should be less than what you paid)
  • Calculator: Use a calculator to double-check your subtraction
  • Reverse calculation: What you paid - change should equal cost

Always verify your work to catch mistakes early!