Add Whole Tens

Teaching Notes

Emphasize adding tens affects only the tens place.

Common Mistakes

• Adding to the ones digit
• Incorrectly identifying tens place
• Forgetting to update the tens value

Differentiation

Discussion Questions

• How does adding 10, 20, or 30 change a number?
• What part of the number stays the same?
• When is it useful to add whole tens mentally?
• Can this strategy be used with other numbers?

Skill Cluster

Number Sense & Mental Math

Estimated Time

8 minutes

Skills Practiced

Prerequisites

• mental_addition_basics
• Counting by 10s
• Place Value (Tens and Ones)
• Adding 10 to a 2-digit number

Next Steps

• Subtract Whole Tens
• Add 2-Digit Numbers (No Regrouping)
• Add Whole Hundreds
• Subtract Whole Tens - Set A
• Add Whole Hundreds - Set A
• Add 2-Digit Numbers No Regrouping - Set A