Math Worksheet for 20-Year-Old Students

Instructions

1. Complete each activity in order.
2. Write neatly and show your thinking.
3. You may use counters, small objects, or draw pictures to help you.
4. Check your work when you reach the Answer Key.

Mission: Explore the Number 20

You are helping a shopkeeper organize 20 items. Complete the activities to unlock each part of the shop.

1. Count to 20

Fill in the missing numbers.

1. 1, 2, 3, _____, 5, 6
2. 7, _____, 9, 10, 11
3. 12, 13, _____, 15, 16
4. 17, _____, 19, 20
5. _____, 2, 3, 4, 5
6. 15, 16, 17, , 19,

2. Build the Number 20

Remember: 20 is 2 tens and 0 ones.

Complete each sentence.

1. 20 has tens and ones.
2. 1 ten and 10 ones make _____.
3. 2 tens make _____.
4. The number before 20 is _____.
5. The number after 20 is _____.
6. 20 is greater than and less than .

3. Show 20 in Different Ways

Complete the organizer. The example shows how to begin.

4. Compare Numbers

Write greater than, less than, or equal to.

1. 20 is __ 18.
2. 14 is __ 20.
3. 20 is __ 20.
4. 19 is __ 20.
5. 20 is __ 12.

You may use the symbols >, <, or = if your teacher or family member asks you to.

5. Add and Subtract

Solve each problem. Use drawings or counters if you need help.

1. 10 + 10 = _____
2. 12 + 8 = _____
3. 15 + 5 = _____
4. 20 - 1 = _____
5. 20 - 6 = _____
6. 18 - 8 = _____
7. 9 + 9 = _____
8. 20 - 10 = _____

Hint: When adding numbers that make 20, think about pairs such as 10 and 10 or 12 and 8.

6. Real-World Shop Problems

Read each situation. Write an equation and solve it.

1. The shopkeeper has 12 red apples and 8 green apples. How many apples are there altogether?

   Equation: __

   Answer: _____ apples

2. There are 20 pencils. The shopkeeper sells 7 pencils. How many pencils are left?

   Equation: __

   Answer: _____ pencils

3. A shelf holds 20 books. There are 14 books on the shelf. How many more books are needed to fill the shelf?

   Equation: __

   Answer: _____ books

4. You have 10 coins and find 10 more coins. How many coins do you have now?

   Equation: __

   Answer: _____ coins

7. Make Your Own Number Story

Create a story problem that uses the number 20.

• Draw a picture of your story.
• Write an addition or subtraction equation.
• Write the answer.

Story: ____

Equation: __

Answer: ___

Optional Challenge

1. Find three different addition equations that equal 20.

   a. __

   b. __

   c. __

2. I am a number between 10 and 20. I have 1 ten and 6 ones. What number am I?

   Answer: _____

3. There are 20 toy cars. They are placed equally into 4 boxes. How many toy cars go in each box?

   Answer: _____ toy cars in each box

Reflection

Circle or explain your answer.

The activity that helped me understand 20 best was:

• Counting
• Drawing
• Adding
• Subtracting
• Solving a story problem

One thing I can do with the number 20 in real life is:

Answer Key

1. Count to 20

1. 4
2. 8
3. 14
4. 18, 20
5. 1
6. 18, 20

2. Build the Number 20

1. 2 tens and 0 ones
2. 20
3. 20
4. 19
5. 21
6. Answers will vary. Example: 20 is greater than 19 and less than 21.

3. Show 20 in Different Ways

Answers may vary. Possible answers include:

• Addition: 15 + 5 = 20
• Subtraction: 20 - 10 = 10
• Tens and ones: 2 tens + 0 ones
• Number word: twenty
• Drawing: Any drawing showing 20 objects

4. Compare Numbers

1. greater than
2. less than
3. equal to
4. less than
5. greater than

5. Add and Subtract

1. 20
2. 20
3. 20
4. 19
5. 14
6. 10
7. 18
8. 10

6. Real-World Shop Problems

1. 12 + 8 = 20; 20 apples
2. 20 - 7 = 13; 13 pencils
3. 20 - 14 = 6; 6 books
4. 10 + 10 = 20; 20 coins

7. Make Your Own Number Story

Answers will vary. The equation should use addition or subtraction and should correctly match the story.

Optional Challenge

1. Answers may vary. Examples: 10 + 10 = 20, 12 + 8 = 20, and 15 + 5 = 20.
2. 16
3. 5 toy cars in each box