Shark Learning
Fourth/Addition

Adding whole tens

Practice adding two whole tens (multiples of 10) to build fast mental addition with tens.
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Practice Questions

  1. 30 + 80 = ?
    Show answer

    110

  2. 40 + 50 = ?
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    90

  3. 70 + 20 = ?
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    90

  4. 60 + 30 = ?
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    90

  5. 20 + 90 = ?
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    110

Teacher Resources
Teaching Notes

This activity builds fluency in adding multiples of 10, a foundational mental math skill for second graders. Emphasize the connection between basic addition facts (e.g., 3+4=7) and adding tens (30+40=70) through place value understanding.

Vocabulary
Whole tens: Numbers like 10, 20, 30, etc.
Add: To combine numbers.
Common Mistakes
  • Forgetting the zero when adding tens (e.g., 30+40=7).
  • Treating tens as ones (e.g., confusing 3 tens + 4 tens with 3 ones + 4 ones).
  • Difficulty transferring single-digit addition knowledge to tens.
Differentiation
SupportUse concrete manipulatives like base ten blocks or a number line to visualize adding groups of ten. Provide a reference chart for counting by tens.
ChallengeChallenge students to add three multiples of ten or to add a multiple of ten to a two-digit number (e.g., 25 + 30). Encourage explaining their mental strategies.
Discussion Questions
  • How is adding 20 + 60 similar to adding 2 + 6?
  • Why is understanding place value important when adding tens?
  • When might you use mental math to add tens in real life?
Extension Activities
  • Use a number line to skip count by tens.
  • Create addition stories with tens.
  • Play with base-ten blocks.
Parent Tip

Use coins like dimes to represent tens and practice adding them.

Learning Path
Skill Cluster

Number Sense & Operations

Estimated Time

15 minutes

Skills Practiced
Adding whole tensSkip counting by tensPlace value tens