Day 12 of 30
Multiply 2-digit by 1-digit numbers
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Learning Objective
Students will be able to multiply 2-digit by 1-digit numbers.
In this lesson, we'll explore how to multiply 2-digit by 1-digit numbers. Mathematical thinking develops logical reasoning and problem-solving abilities.
Multi-digit multiplication and division extend basic facts using place value. Multiplying by multiples of 10: 6 × 40 = 6 × 4 × 10 = 24 × 10 = 240. Multiply the non-zero digits, then attach the zeros. Multiplying 2-digit by 1-digit: use the area model (24 × 6 = 20×6 + 4×6 = 120 + 24 = 144) or the standard algorithm (multiply ones, multiply tens, add). Multiplying 2-digit by 2-digit: FOIL-like approach: (23 × 47 = 20×40 + 20×7 + 3×40 + 3×7 = 800 + 140 + 120 + 21 = 1081). Division by 2-digit divisors: estimate the quotient using compatible numbers (372 ÷ 43: think 43 ≈ 40; 360 ÷ 40 = 9; try 9, check 9×43=387 too big; try 8, check 8×43=344; remainder 372−344=28). Long division practice builds number sense and prepares for algebra.
As you work through today's material, pay attention to the examples and try to identify the patterns or strategies being used. This will help you apply these concepts to new problems.
Take notes on key points and make connections to what you've already learned in previous lessons.
A mathematical question requiring analysis and solution
The result obtained by solving a problem
Instructions
Materials Needed
- Notebook
- Calculator (if needed)
- Graph paper
Practice Problem 1: Apply what you learned today.
Practice Problem 2: Try a similar problem on your own.
Challenge: Can you create your own problem like the ones we practiced?
Teaching Tip
For this age group: Balance direct instruction with collaborative activities. Allow students to explain their thinking and make connections to prior knowledge when exploring multiply 2-digit by 1-digit numbers.