Grade 1 Addition Worksheets - free & printable | Worsheets library - Free Printable

Problem Description:

The task is to solve a series of addition problems involving whole tens (two-digit numbers). The worksheet is designed for Grade 1 students and focuses on adding two-digit numbers that are multiples of 10.

Solution Approach:

To solve each problem, we will add the two given numbers step by step. Since all the numbers are multiples of 10, the addition is straightforward. We simply add the tens digits and append a zero at the end.

Step-by-Step Solutions:

#### Problem 1: \( 20 + 70 \)
- Add the tens digits: \( 2 + 7 = 9 \)
- Append a zero: \( 90 \)
- Answer: \( 90 \)

#### Problem 2: \( 80 + 50 \)
- Add the tens digits: \( 8 + 5 = 13 \)
- Append a zero: \( 130 \)
- Answer: \( 130 \)

#### Problem 3: \( 20 + 40 \)
- Add the tens digits: \( 2 + 4 = 6 \)
- Append a zero: \( 60 \)
- Answer: \( 60 \)

#### Problem 4: \( 40 + 20 \)
- Add the tens digits: \( 4 + 2 = 6 \)
- Append a zero: \( 60 \)
- Answer: \( 60 \)

#### Problem 5: \( 30 + 60 \)
- Add the tens digits: \( 3 + 6 = 9 \)
- Append a zero: \( 90 \)
- Answer: \( 90 \)

#### Problem 6: \( 80 + 60 \)
- Add the tens digits: \( 8 + 6 = 14 \)
- Append a zero: \( 140 \)
- Answer: \( 140 \)

#### Problem 7: \( 10 + 70 \)
- Add the tens digits: \( 1 + 7 = 8 \)
- Append a zero: \( 80 \)
- Answer: \( 80 \)

#### Problem 8: \( 60 + 10 \)
- Add the tens digits: \( 6 + 1 = 7 \)
- Append a zero: \( 70 \)
- Answer: \( 70 \)

#### Problem 9: \( 50 + 30 \)
- Add the tens digits: \( 5 + 3 = 8 \)
- Append a zero: \( 80 \)
- Answer: \( 80 \)

#### Problem 10: \( 10 + 70 \)
- Add the tens digits: \( 1 + 7 = 8 \)
- Append a zero: \( 80 \)
- Answer: \( 80 \)

#### Problem 11: \( 70 + 30 \)
- Add the tens digits: \( 7 + 3 = 10 \)
- Append a zero: \( 100 \)
- Answer: \( 100 \)

#### Problem 12: \( 50 + 40 \)
- Add the tens digits: \( 5 + 4 = 9 \)
- Append a zero: \( 90 \)
- Answer: \( 90 \)

#### Problem 13: \( 30 + 30 \)
- Add the tens digits: \( 3 + 3 = 6 \)
- Append a zero: \( 60 \)
- Answer: \( 60 \)

#### Problem 14: \( 60 + 60 \)
- Add the tens digits: \( 6 + 6 = 12 \)
- Append a zero: \( 120 \)
- Answer: \( 120 \)

#### Problem 15: \( 80 + 80 \)
- Add the tens digits: \( 8 + 8 = 16 \)
- Append a zero: \( 160 \)
- Answer: \( 160 \)

#### Problem 16: \( 70 + 40 \)
- Add the tens digits: \( 7 + 4 = 11 \)
- Append a zero: \( 110 \)
- Answer: \( 110 \)

#### Problem 17: \( 30 + 20 \)
- Add the tens digits: \( 3 + 2 = 5 \)
- Append a zero: \( 50 \)
- Answer: \( 50 \)

#### Problem 18: \( 50 + 10 \)
- Add the tens digits: \( 5 + 1 = 6 \)
- Append a zero: \( 60 \)
- Answer: \( 60 \)

#### Problem 19: \( 50 + 60 \)
- Add the tens digits: \( 5 + 6 = 11 \)
- Append a zero: \( 110 \)
- Answer: \( 110 \)

#### Problem 20: \( 60 + 70 \)
- Add the tens digits: \( 6 + 7 = 13 \)
- Append a zero: \( 130 \)
- Answer: \( 130 \)

Final Answers:

\[
\begin{aligned}
&1.~ 90 & 2.~ 130 \\
&3.~ 60 & 4.~ 60 \\
&5.~ 90 & 6.~ 140 \\
&7.~ 80 & 8.~ 70 \\
&9.~ 80 & 10.~ 80 \\
&11.~ 100 & 12.~ 90 \\
&13.~ 60 & 14.~ 120 \\
&15.~ 160 & 16.~ 110 \\
&17.~ 50 & 18.~ 60 \\
&19.~ 110 & 20.~ 130 \\
\end{aligned}
\]

Boxed Final Answer:

\[
\boxed{
\begin{aligned}
&1.~ 90 & 2.~ 130 \\
&3.~ 60 & 4.~ 60 \\
&5.~ 90 & 6.~ 140 \\
&7.~ 80 & 8.~ 70 \\
&9.~ 80 & 10.~ 80 \\
&11.~ 100 & 12.~ 90 \\
&13.~ 60 & 14.~ 120 \\
&15.~ 160 & 16.~ 110 \\
&17.~ 50 & 18.~ 60 \\
&19.~ 110 & 20.~ 130 \\
\end{aligned}
}
\]