Activities to Teach Students to Multiply 2-Digit Numbers by Larger Numbers
As a teacher, it’s essential to have methods to help your students learn and understand complicated mathematical concepts such as multiplying 2-digit numbers by larger numbers. It can be overwhelming for students, but with interactive and engaging activities, learning can be fun and easy.
Here are some activities you can do in your classroom to teach your students multiplication techniques that can help them understand the multiplication of 2-digit numbers by larger numbers.
1. Expanded Form
Multiplying two two-digit numbers is easier if you break them down into expanded form, which means representing them as the sum of their constituent parts.
Consider the problem 25 x 13. Break down these numbers to 20+5 and 10+3, respectively. Then, multiply each constituent part. Twenty times ten is 200, twenty times three is 60, five times ten is 50, and five times three is 15. Add the products to get the final answer, which is 325.
Using expanded form helps students understand the mechanics of multiplication and makes it easier to break down problems step-by-step, especially when the numbers get larger.
2. Place Value Chart
A place value chart is a grid that helps students visualize the place value of digits in a number. Begin by writing the first number at the top of the chart and the second number on the left side. Ask the students to fill in each box by multiplying the digits in each corresponding row and column.
Consider the problem 46 x 25. Complete the place value chart by multiplying 6, 4, 2, and 5. Write the answer at the intersection of the two digits. 46 x 25 becomes 1,150.
Using a place value chart is instrumental in helping students understand the concept of place value, making it easier for them to multiply 2-digit numbers by larger numbers.
3. Lattice Method
The lattice method is a multiplication technique that uses a grid of boxes to separate the digits of each number. Draw a grid of boxes equal to the sum of the digits in each number. In the case of 25 x 13, draw a two by two grid. Write the digits of each number along the top and left side of the grid. Multiply the digits in each box diagonally, and write the answer in each box.
In the grid, multiply 3×5, 3×2, 1×5, and 1×2. Carry over any digits more than ten. Add the diagonal rows to get the answer. In this case, the answer is 325.
The lattice method is one of the many activities that can help students understand the multiplication of 2-digit numbers by larger numbers.
4. Repeated Addition
Repeated addition is a technique used to demonstrate that multiplication is the same as adding the same number repeatedly. For example, 5 x 7 is the same as 5+5+5+5+5+5+5.
For a 2-digit number multiplied by a larger number, students can break down the larger number into smaller factors and add the first number multiplied by each factor.
For example, in 25 x 13, break down 13 into 10+3. Then add 25+250 (the first number times the 10s place) and 75 (the first number times the ones place). The final answer is 325.
Repeated addition mostly requires students to memorize multiplication facts, making multiplication problems much easier and more accessible.
Multiplying 2-digit numbers by larger numbers is a fundamental math skill that students must learn. By using interactive and engaging activities, teachers can help students understand the mechanics of multiplication and get them confident in applying these techniques on their own. Using expanded form, place value chart, the lattice method, and repeated addition can make multiplication a breeze for students and help them excel in math.