Math worksheet for practicing counting in 10s, 100s, and 1000s with abacus and number pattern exercises.

Let's solve each part of the worksheet step by step and explain the reasoning.

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1. Abacus Problem: Counting in 10s, 100s, and 1000s

We are given a number: 4825
We need to find:

#### a. 10 more than 4825
Add 10 to 4825:
$$
4825 + 10 = 4835
$$
✔ Answer: 4835 (already filled in)

#### b. 100 less than 4825
Subtract 100 from 4825:
$$
4825 - 100 = 4725
$$
✔ Answer: 4725

#### c. 1000 more than 4825
Add 1000 to 4825:
$$
4825 + 1000 = 5825
$$
✔ Answer: 5825

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2. Number Patterns – Write the next three numbers

#### Pattern 1:
2347, 3347, 4347, 5347, 6347, 7347

- Each number increases by 1000
- So:
$$
4347 + 1000 = 5347 \\
5347 + 1000 = 6347 \\
6347 + 1000 = 7347
$$

✔ Next three numbers: 5347, 6347, 7347 (already filled in)

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#### Pattern 2:
8801, 8811, 8821, ____, ____, ____

- Look at the pattern:
$$
8801 → 8811 \quad (+10) \\
8811 → 8821 \quad (+10)
$$
- So, add 10 each time:
$$
8821 + 10 = 8831 \\
8831 + 10 = 8841 \\
8841 + 10 = 8851
$$

✔ Next three numbers: 8831, 8841, 8851

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#### Pattern 3:
3451, 3351, 3251, ____, ____, ____

- Decreasing by 100 each time:
$$
3451 - 100 = 3351 \\
3351 - 100 = 3251 \\
3251 - 100 = 3151 \\
3151 - 100 = 3051 \\
3051 - 100 = 2951
$$

✔ Next three numbers: 3151, 3051, 2951

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3. Write the missing numbers

#### First sequence:
3861, 3761, 3661, 3561, 3461, 3361

- This is decreasing by 100 each time:
$$
3861 - 100 = 3761 \\
3761 - 100 = 3661 \\
3661 - 100 = 3561 \\
3561 - 100 = 3461 \\
3461 - 100 = 3361
$$

✔ All correct as filled in.

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#### Second sequence:
581, 591, ____, ____, ____, 631

- Let’s look at the first two:
$$
581 → 591 \quad (+10)
$$
- So it increases by 10 each time:
$$
591 + 10 = 601 \\
601 + 10 = 611 \\
611 + 10 = 621 \\
621 + 10 = 631
$$

So the missing numbers are: 601, 611, 621

✔ Missing numbers: 601, 611, 621

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#### Third sequence:
____, 2111, ____, ____, 1811, 1711

- We see the last two: 1811 → 1711 → -100
- So likely decreasing by 100 each time.
- Work backward from 2111:
$$
2111 - 100 = 2011 \\
2011 - 100 = 1911 \\
1911 - 100 = 1811 \\
1811 - 100 = 1711
$$

So the sequence is:
- 2211 → 2111 → 2011 → 1911 → 1811 → 1711

Wait — let’s check:
If the pattern is -100, then:
- Before 2111: $ 2111 + 100 = 2211 $
- After 2111: $ 2111 - 100 = 2011 $
- Then: 1911, 1811, 1711

✔ So the missing numbers are:
- First blank: 2211
- Then: 2011, 1911

Sequence: 2211, 2111, 2011, 1911, 1811, 1711

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✔ Final Answers Summary:

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#### 1. Abacus
a. 10 more than 4825 = 4835
b. 100 less than 4825 = 4725
c. 1000 more than 4825 = 5825

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#### 2. Patterns
- 2347, 3347, 4347, 5347, 6347, 7347
- 8801, 8811, 8821, 8831, 8841, 8851
- 3451, 3351, 3251, 3151, 3051, 2951

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#### 3. Missing Numbers
- 3861, 3761, 3661, 3561, 3461, 3361 (correct)
- 581, 591, 601, 611, 621, 631
- 2211, 2111, 2011, 1911, 1811, 1711

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