In Kitty’s 4th/5th math classes, we have been learning about strategies for multiplying larger numbers. The first strategy we learned was called “take apart” multiplication. This method involves breaking apart multiplication expressions into a combination of simpler expressions using the distributive property.
The second method we practiced was “front end” multiplication and it was useful when multiplying with friendly ones, tens and hundreds (30 x 20 or 300 x 40). This was also an opportunity to teach students where a comma goes in a number and that the answer to a multiplication problem is called the product. Allowing students to choose the method that makes the most sense to them deepens their understanding.
After learning and practicing these strategies, we played a game called “Multiplication Compare.” Each pair of students turned over 2 cards from their deck of numbers (300 and 10/ 40 and 500). They each found the product of their 2 numbers (3,000 and 20,000). The person with the larger product wins. The games were lively and focused on the math.
Regardless of the method used, knowing the multiplication facts quickly and accurately greatly improves students’ ability to solve these problems efficiently, without becoming bogged down in the arithmetic.