Math Worksheet for 20-Year-Old Students

Instructions

1. Complete the questions in order. The problems begin with counting and place value, then become more challenging.
2. Show your thinking for addition, subtraction, and word problems.
3. You may use counters, drawings, or a number line to help you.
4. Check your answers when you finish.

Part 1: Counting and Number Sense

1. Write the number that comes before 20: __

2. Write the number that comes after 20: __

3. Count by 2s. Fill in the missing numbers:

   2, 4, 6, 8, 10, 12, 14, 16, 18, __

4. Count backward from 20. Write the next five numbers:

   20, __, __, __, __, __

5. Circle all the numbers that are greater than 20:

   12 19 21 25 18 30

6. Put these numbers in order from least to greatest:

   20, 7, 15, 3, 12

   Answer: __, __, __, __, __

Part 2: Place Value

7. Complete the sentences.

   • 20 has __ tens and __ ones.
   • The digit in the tens place is __.
   • The digit in the ones place is __.

8. Write each number in expanded form.

   • 20 = __ + __
   • 24 = __ + __
   • 29 = __ + __

9. Match each number to its description. Write the letter on the line.

   • 17: __
   • 20: __
   • 32: __

   A. 3 tens and 2 ones B. 1 ten and 7 ones C. 2 tens and 0 ones

Part 3: Addition and Subtraction

10. Solve.

    • 10 + 10 = __
    • 12 + 8 = __
    • 15 + 5 = __
    • 9 + 11 = __

11. Solve.

    • 20 - 10 = __
    • 20 - 7 = __
    • 18 - 8 = __
    • 25 - 5 = __

12. Complete each fact family.

    • 12 + 8 = 20
    • 8 + 12 = __
    • 20 - 12 = __
    • 20 - 8 = __

13. Find the missing number.

    • __ + 6 = 20
    • 14 + __ = 20
    • 20 - __ = 13
    • __ - 4 = 16

14. Choose the correct sign: <, >, or =.

    • 20 __ 18
    • 15 __ 20
    • 20 __ 20
    • 9 + 11 __ 20

Part 4: Real-World Math

15. A box holds 20 crayons. Mia takes out 6 crayons. How many crayons are left?

    Number sentence: __

    Answer: __ crayons

16. A classroom has 12 students in the morning and 8 students join later. How many students are there altogether?

    Number sentence: __

    Answer: __ students

17. A baker makes 20 muffins. She sells 13 muffins. How many muffins remain?

    Number sentence: __

    Answer: __ muffins

18. You have 20 points in a game. You earn 5 more points and then lose 3 points. How many points do you have now?

    Number sentence: __

    Answer: __ points

Part 5: Show What You Know

19. Draw 20 objects in the space below. You may draw stars, dots, circles, or another object. Then group them into tens.

    Drawing space:

    ---

    ---

    ---

    How many groups of ten did you make? __

20. Challenge: Find two different addition equations that equal 20. Neither equation may be 10 + 10.

    • __ + __ = 20
    • __ + __ = 20

Optional Extension

Create a real-life story problem with an answer of 20. Write the problem and solve it.

Problem: ____

Solution: ___

Answer Key

1. 19

2. 21

3. 20

4. 19, 18, 17, 16, 15

5. 21, 25, 30

6. 3, 7, 12, 15, 20

7. 2 tens and 0 ones; tens digit: 2; ones digit: 0

8. 20 = 20 + 0; 24 = 20 + 4; 29 = 20 + 9

9. 17: B; 20: C; 32: A

10. 20, 20, 20, 20

11. 10, 13, 10, 20

12. 20, 8, 12

13. 14, 6, 7, 20

14. , <, =, =

15. 20 - 6 = 14; 14 crayons

16. 12 + 8 = 20; 20 students

17. 20 - 13 = 7; 7 muffins

18. 20 + 5 - 3 = 22; 22 points

19. Answers will vary. The drawing should show 20 objects, organized as 2 groups of 10.

20. Answers will vary. Examples: 9 + 11 = 20 and 15 + 5 = 20.

Optional Extension: Answers will vary, but the story problem should be solved correctly with an answer of 20.