Unit 1 - Numbers to 1000: Practice counting in steps and ordering numbers.

Problem Analysis:

The task involves completing number sequences and ordering numbers. Let's break it down step by step.

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Task 1: Count in steps of 10 to complete the number sequences

#### Sequence 1:
15, 25, __, 45, 55, __

- The sequence increases by 10 each time.
- Missing number after 25: \( 25 + 10 = 35 \)
- Missing number after 55: \( 55 + 10 = 65 \)

Completed sequence:
15, 25, 35, 45, 55, 65

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#### Sequence 2:
173, 183, __, __, 213, __

- The sequence increases by 10 each time.
- Missing number after 183: \( 183 + 10 = 193 \)
- Missing number after 193: \( 193 + 10 = 203 \)
- Missing number after 213: \( 213 + 10 = 223 \)

Completed sequence:
173, 183, 193, 203, 213, 223

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#### Sequence 3:
436, __, 416, __, __, 386

- The sequence decreases by 10 each time.
- Missing number before 416: \( 436 - 10 = 426 \)
- Missing number after 416: \( 416 - 10 = 406 \)
- Missing number after 406: \( 406 - 10 = 396 \)

Completed sequence:
436, 426, 416, 406, 396, 386

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#### Sequence 4:
721, 711, __, 791, __, __

- The sequence alternates between decreasing by 10 and increasing by 80.
- Missing number after 711: \( 711 - 10 = 701 \)
- Missing number after 791: \( 791 + 80 = 871 \)
- Missing number after 871: \( 871 + 80 = 951 \)

Completed sequence:
721, 711, 701, 791, 871, 951

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Task 2: Count in steps of 100 to complete the number sequences

#### Sequence 1:
344, __, __, __

- The sequence increases by 100 each time.
- Missing number after 344: \( 344 + 100 = 444 \)
- Missing number after 444: \( 444 + 100 = 544 \)
- Missing number after 544: \( 544 + 100 = 644 \)

Completed sequence:
344, 444, 544, 644

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#### Sequence 2:
__ , 632, __, __

- The sequence increases by 100 each time.
- Missing number before 632: \( 632 - 100 = 532 \)
- Missing number after 632: \( 632 + 100 = 732 \)
- Missing number after 732: \( 732 + 100 = 832 \)

Completed sequence:
532, 632, 732, 832

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#### Sequence 3:
__ , __, 711, __

- The sequence increases by 100 each time.
- Missing number before 711: \( 711 - 100 = 611 \)
- Missing number before 611: \( 611 - 100 = 511 \)
- Missing number after 711: \( 711 + 100 = 811 \)

Completed sequence:
511, 611, 711, 811

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Task 3: Order these numbers from smallest to largest

#### Set 1:
31, 56, 103, 13

- Arrange in ascending order:
13, 31, 56, 103

Ordered sequence:
13, 31, 56, 103

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#### Set 2:
176, 671, 716, 167

- Arrange in ascending order:
167, 176, 671, 716

Ordered sequence:
167, 176, 671, 716

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Final Answer:

1. Completed Sequences (Step of 10):
- 15, 25, 35, 45, 55, 65
- 173, 183, 193, 203, 213, 223
- 436, 426, 416, 406, 396, 386
- 721, 711, 701, 791, 871, 951

2. Completed Sequences (Step of 100):
- 344, 444, 544, 644
- 532, 632, 732, 832
- 511, 611, 711, 811

3. Ordered Numbers:
- 13, 31, 56, 103
- 167, 176, 671, 716

Boxed Final Answer:
\[
\boxed{
\begin{array}{l}
\text{1. } 15, 25, 35, 45, 55, 65 \\
\text{ } 173, 183, 193, 203, 213, 223 \\
\text{ } 436, 426, 416, 406, 396, 386 \\
\text{ } 721, 711, 701, 791, 871, 951 \\
\text{2. } 344, 444, 544, 644 \\
\text{ } 532, 632, 732, 832 \\
\text{ } 511, 611, 711, 811 \\
\text{3. } 13, 31, 56, 103 \\
\text{ } 167, 176, 671, 716
\end{array}
}
\]