Grade 3 · Choose the nearer hundred · 290 of 750
Choose the nearer hundred: original count: 645; rounding place: 10
A report for a classroom activity contains a count of 645 and asks for rounding to the nearest 10. Find the rounded report using the stated place and upward midpoint rule, 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
A report for a classroom activity contains a count of 645 and asks for rounding to the nearest 10. First find the rounded report using the stated place and upward midpoint rule. Then answer: What is the absolute difference between the original count and its rounded report?
Use this scratch space or work on paper. Your notes stay on this page and clear when you leave. Answers are for self-checking; they are not automatically graded.
A starting point
Rounding replaces an exact value with a nearby multiple of the selected place. Locate the two neighboring multiples and their midpoint before deciding which neighbor is closer.
Work through the reasoning
Step 1
Identify the quantities and the task
A report for a classroom activity contains a count of 645 and asks for rounding to the nearest 10. The first task is to find the rounded report using the stated place and upward midpoint rule. Rounding replaces an exact value with a nearby multiple of the selected place. Locate the two neighboring multiples and their midpoint before deciding which neighbor is closer.
Step 2
Calculate the original result
645 rounded to the nearest 10 is 650. The rounded value differs from the original by 5. A midpoint tie is rounded to the greater multiple in this investigation.
Step 3
Complete the follow-up calculation
What is the absolute difference between the original count and its rounded report? 5, found from |645 − 650|. This measures rounding difference, not the number of digits removed.
The answer
645 rounded to the nearest 10 is 650. The rounded value differs from the original by 5. A midpoint tie is rounded to the greater multiple in this investigation. Follow-up: 5, found from |645 − 650|. This measures rounding difference, not the number of digits removed.
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
A report for a classroom activity contains a count of 645 and asks for rounding to the nearest 10. Rounding replaces an exact value with a nearby multiple of the selected place. Locate the two neighboring multiples and their midpoint before deciding which neighbor is closer. The rounded value differs from the original by 5. A midpoint tie is rounded to the greater multiple in this investigation.
645 rounded to the nearest 10 is 650
03 · Reflect and transfer
Explain what changes and why.
Keep the original marker in view while its estimate moves toward the chosen endpoint. The original count itself is not being changed. 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.