standard_description: Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
problem_activity: Narrative
This optional activity gives students another opportunity to practice identifying multiples of some powers of 10 that border a given number and identify the nearest ones. As before, students may use number lines to support their reasoning, but here the number lines are unlabeled.
Launch
Groups of 2
Activity
“Work independently for a few minutes. Then, discuss your responses with your partner.”
5 minutes: independent work time
2 minutes: partner discussion
Student Facing
Answer each question. Label and use the number lines if they are helpful.
Is 425,193 closer to 400,000 or 500,000?
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Is 425,193 closer to 420,000 or 430,000?
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Is 425,193 closer to 425,000 or 426,000?
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Is 425,193 closer to 425,100 or to 425,200?
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Is 425,193 closer to 425,190 or to 425,200?
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For the number 425,193:
The nearest multiple of 100,000 is _______________.
The nearest multiple of 10,000 is _______________.
The nearest multiple of 1,000 is _______________.
The nearest multiple of 100 is _______________.
The nearest multiple of 10 is _______________.
Student Response
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Activity Synthesis
Invite students to share their responses and reasoning.
“Which nearest multiples were you able to identify fairly easily?”
“Which were a bit more challenging, if any? Why might that be?”


aligns: no