🔢 Part 1: Understanding the Algorithm

Step 1: Set up the problem vertically

Step 2: Multiply 23 by 5 (the ones digit of 45)

23 × 5 = _______

Step 3: Multiply 23 by 40 (the tens digit of 45, which is 4 × 10)

23 × 40 = _______

Step 4: Add the partial products together

_______ + _______ = _______

📝 Part 2: Guided Practice

Step 1: Multiply by the ones digit (6)

34 × 6 = _______

Step 2: Multiply by the tens digit (20)

34 × 20 = _______

Step 3: Add the partial products

🎯 Part 3: Estimation and Number Sense

Problem: 43 × 29

Estimate: 40 × 30 = _______

Actual calculation:

Is your answer reasonable? Circle one:

Estimate: _____ × _____ = _______

🏆 Part 4: Independent Practice

a) 46 × 35

b) 73 × 28

c) 84 × 57

Estimate: _________________

Calculation:

Answer: There are _______ chairs altogether.

🔍 Part 5: Error Analysis

Sam's working:

25 × 4 = 100

25 × 3 = 75

100 + 75 = 175... but Sam wrote 850