Grade 5 · Multiply a decimal price by a count · 682 of 750
Multiply a decimal price by a count: price per item: 35 cents; item count: 9
An invented budget for a classroom activity lists 9 identical items at $0.35 each. Find the original total price in cents and dollars, explain the calculation, and check a related question.
Try the question, use a hint when you need one, and compare your reasoning with the worked solution. The animation starts with this chapter’s values; changing its controls explores a new case.
01 · Make a prediction
Your practice question
An invented budget for a classroom activity lists 9 identical items at $0.35 each. First find the original total price in cents and dollars. Then answer: What total would one additional item produce?
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A starting point
A decimal price multiplied by a whole count repeats the same cost. Integer-cent arithmetic avoids losing a place value or treating a decimal point as an instruction to round.
Work through the reasoning
Step 1
Identify the quantities and the task
An invented budget for a classroom activity lists 9 identical items at $0.35 each. The first task is to find the original total price in cents and dollars. A decimal price multiplied by a whole count repeats the same cost. Integer-cent arithmetic avoids losing a place value or treating a decimal point as an instruction to round.
Step 2
Calculate the original result
9 × $0.35 = $3.15. The exact total is 315 cents, written $3.15. These are fictional values for learning, not an offer to buy anything.
Step 3
Complete the follow-up calculation
What total would one additional item produce? $3.50, adding another $0.35.
The answer
9 × $0.35 = $3.15. The exact total is 315 cents, written $3.15. These are fictional values for learning, not an offer to buy anything. Follow-up: $3.50, adding another $0.35.
Compare the method as well as the result. A different valid method may reach the same answer. Keep exact values until the last step when the question asks for rounding.
02 · Explore the model
See the mathematical relationship move.
Use Play, Pause, and the timeline to inspect the construction. Reset restores the question’s original settings. The displayed assumptions describe where this model applies.
Watch the relationship
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The mathematical idea
An invented budget for a classroom activity lists 9 identical items at $0.35 each. A decimal price multiplied by a whole count repeats the same cost. Integer-cent arithmetic avoids losing a place value or treating a decimal point as an instruction to round. The exact total is 315 cents, written $3.15. These are fictional values for learning, not an offer to buy anything.
9 × $0.35 = $3.15
03 · Reflect and transfer
Explain what changes and why.
Reveal one item at a time and add its price to the subtotal. Compare the complete subtotal with the product of price and count. Explain which quantity changes and which relationship stays valid. Use the starting values again before checking your written answer.
This is a distinct guided scenario using a reusable mathematical model. Similar-looking diagrams can represent different given values and conclusions; they are not different mathematical theories.