Math worksheet for practicing counting by 50s, 25s, and 10s on number lines up to 1000.

Problem Description:

The task involves completing number lines by adding or subtracting specific values (e.g., 20s, 50s, 10s) to the given starting numbers. The goal is to fill in the missing numbers on each line according to the specified pattern.

Solution Approach:

1. Understand the Pattern: Each row specifies an operation (e.g., "Count by 20s," "Count by 50s") and a starting number.
2. Apply the Operation: Add or subtract the specified value repeatedly to generate the next numbers in the sequence.
3. Fill in the Missing Numbers: Use the pattern to complete the number line for each row.

Step-by-Step Solution:

#### Row I: Count by 20s
- Starting number: 100
- Sequence: \( 100, 120, 140, 160, 180, 200 \)
- Next number: \( 200 + 20 = 220 \)

#### Row II: Count by 50s
- Starting number: 500
- Sequence: \( 500, 550, 600, 650, 700, 750 \)
- Next number: \( 750 + 50 = 800 \)

#### Row III: Count by 10s
- Starting number: 30
- Sequence: \( 30, 40, 50, 60, 70, 80 \)
- Next number: \( 80 + 10 = 90 \)

#### Row IV: Count by 10s
- Starting number: 100
- Sequence: \( 100, 110, 120, 130, 140, 150 \)
- Next number: \( 150 + 10 = 160 \)

#### Row V: Count by 50s
- Starting number: 200
- Sequence: \( 200, 250, 300, 350, 400, 450 \)
- Next number: \( 450 + 50 = 500 \)

#### Row VI: Count by 10s
- Starting number: 310
- Sequence: \( 310, 320, 330, 340, 350, 360 \)
- Next number: \( 360 + 10 = 370 \)

Final Answer:

The completed number lines are as follows:

1. Row I: \( 100, 120, 140, 160, 180, 200, 220 \)
2. Row II: \( 500, 550, 600, 650, 700, 750, 800 \)
3. Row III: \( 30, 40, 50, 60, 70, 80, 90 \)
4. Row IV: \( 100, 110, 120, 130, 140, 150, 160 \)
5. Row V: \( 200, 250, 300, 350, 400, 450, 500 \)
6. Row VI: \( 310, 320, 330, 340, 350, 360, 370 \)

\[
\boxed{
\begin{array}{ccccccc}
\text{Row I} & 100 & 120 & 140 & 160 & 180 & 200 & 220 \\
\text{Row II} & 500 & 550 & 600 & 650 & 700 & 750 & 800 \\
\text{Row III} & 30 & 40 & 50 & 60 & 70 & 80 & 90 \\
\text{Row IV} & 100 & 110 & 120 & 130 & 140 & 150 & 160 \\
\text{Row V} & 200 & 250 & 300 & 350 & 400 & 450 & 500 \\
\text{Row VI} & 310 & 320 & 330 & 340 & 350 & 360 & 370 \\
\end{array}
}
\]