Grade 2 · Read hundreds tens and ones · 317 of 750
Read hundreds tens and ones: hundreds digit: 9; tens digit: 0; ones digit: 9
An inventory at a classroom activity records 9 hundreds, 0 tens, and 9 ones of counters. Find the total represented by the hundreds, tens, and ones, 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 inventory at a classroom activity records 9 hundreds, 0 tens, and 9 ones of counters. First find the total represented by the hundreds, tens, and ones. Then answer: What number results when one additional ten-pack is added?
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A starting point
The same written digit has a different value in each place. A zero contributes no units in its place but preserves the positions of the other digits.
Work through the reasoning
Step 1
Identify the quantities and the task
An inventory at a classroom activity records 9 hundreds, 0 tens, and 9 ones of counters. The first task is to find the total represented by the hundreds, tens, and ones. The same written digit has a different value in each place. A zero contributes no units in its place but preserves the positions of the other digits.
Step 2
Calculate the original result
9 × 100 + 0 × 10 + 9 = 909. The inventory is 909. Its expanded parts are 900, 0, and 9.
Step 3
Complete the follow-up calculation
What number results when one additional ten-pack is added? 919. Adding ten increases the total by 10, even if a new hundred must be regrouped.
The answer
9 × 100 + 0 × 10 + 9 = 909. The inventory is 909. Its expanded parts are 900, 0, and 9. Follow-up: 919. Adding ten increases the total by 10, even if a new hundred must be regrouped.
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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From experiment to screen.
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The mathematical idea
An inventory at a classroom activity records 9 hundreds, 0 tens, and 9 ones of counters. The same written digit has a different value in each place. A zero contributes no units in its place but preserves the positions of the other digits. The inventory is 909. Its expanded parts are 900, 0, and 9.
9 × 100 + 0 × 10 + 9 = 909
03 · Reflect and transfer
Explain what changes and why.
Reveal hundreds, tens, and ones in order. Add their values rather than adding the three digit symbols as if they were all ones. 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.