Subtracting Tens from 3-Digit Numbers (265)

Teaching Notes

Emphasize place value when subtracting tens. Students should recognize that only the tens digit changes, unless the number of tens becomes negative and requires borrowing from the hundreds place (which is less common with 'whole tens' but possible if, for example, 300-50). Focus on mental math strategies.

Vocabulary

Align digits: Place digits in correct columns.

Regrouping: Borrowing from a higher place value.

Common Mistakes

• Subtracting from the wrong place value (e.g., subtracting tens from the ones digit).
• Confusing subtracting tens with subtracting ones or hundreds.
• Forgetting to adjust the hundreds digit if regrouping is implicitly needed (e.g., 200 - 30, though the prompt implies simpler cases like 350 - 20).

Differentiation

Discussion Questions

• When we subtract a whole ten, which digit(s) in the 3-digit number change?
• How is subtracting 20 from 350 similar to subtracting 2 from 35?
• Can you think of a real-life situation where you would subtract whole tens from a 3-digit number?

Extension Activities

• Subtract tens and ones.
• Create word problems.

Parent Tip

Use base-ten blocks to demonstrate subtracting tens.

Skill Cluster

Number Sense & Operations

Estimated Time

15 minutes

Skills Practiced

Prerequisites

• Place Value to 999
• Subtracting Multiples of Ten (within 100)
• Subtracting 2-Digit Numbers (no regrouping)

Next Steps

• Subtracting Multiples of 100 from 3-Digit Numbers
• Subtracting 2-Digit Numbers from 3-Digit Numbers (no regrouping)
• Subtracting 3-Digit Numbers (no regrouping)
• Subtract Whole Hundreds from 3-Digit Numbers
• Subtract Any Ten from 3-Digit Numbers (no regrouping)