Overview
This lecture explains simple, step-by-step strategies for helping students memorize multiplication tables by breaking them into manageable patterns and using counting techniques.
Breaking Down the Multiplication Table
- The full multiplication table appears as a 10x10 grid (100 problems), but many can be eliminated using patterns.
- Multiplying by 1 is straightforward; 1 × any number equals that number.
- After removing the 1s, focus on the remaining 9x9 grid.
Strategies for Each Number Set
- Twos: Emphasize that 2 × n is the same as n + n; practice counting by twos (2, 4, 6, 8, etc.).
- Threes: Use a plus three strategy; each result adds three to the previous one (e.g., 3, 6, 9, 12...).
- Fours: Use a plus four strategy; add four each time (4, 8, 12, 16...) and practice counting by fours.
- Fives: Fives always end in 0 (even multipliers) or 5 (odd multipliers); practice counting by fives (5, 10, 15...).
- After removing 1s–5s, the remaining grid gets smaller and easier to memorize.
The Nines Trick
- The digits of any product of 9 add to nine (e.g., 9 × 3 = 27; 2 + 7 = 9).
- The first digit of the product is always one less than the multiplier (9 × 4 = 36; 3 is one less than 4).
- Use these checks for quick verification of answers.
Memorizing the Remaining Squares
- Square numbers are often easier to remember (e.g., 6 × 6 = 36, 7 × 7 = 49, 8 × 8 = 64).
- Only three more challenging combinations remain: 6 × 7 (42), 6 × 8 (48), and 7 × 8 (56).
Key Terms & Definitions
- Multiplication Table — A chart that lists the products of numbers, typically 1 through 10.
- Plus Strategy — A method of learning multiplication by repeated addition (e.g., plus three for threes).
- Square Numbers — The result of multiplying a number by itself (e.g., 7 × 7 = 49).
Action Items / Next Steps
- Practice the plus strategies (twos, threes, fours) and counting aloud by these numbers.
- Test understanding by asking random multiplication questions within each set.
- Memorize the three remaining challenging products: 6 × 7, 6 × 8, and 7 × 8.