Welcome to Math Night for Parents of 4th Grade Students Multiplication & Division Methods

Multiplication This is how most of us learned to multiply: 7 15 12 9 Now, just add the bottom 2 rows of numbers, regrouping as needed. Erase or cross off the numbers you carried. 12 9 6 x 5 = 30 6 x 4 = 24 13 30 + 2 = 32 1 8 7 x 4 = 28 Write a zero in the ones place. Write the 8 in the ones place. 2 10 Write the 4 in the tens place. 3 11 Carry the 2 to the tens place. Carry the 2 to the hundreds place. 4 5 7 x 5 = 35 35 + 2 = 37 14 Write 32 in the hundreds & thousands places. 6 Write 37 in the hundreds and tens place.

Traditional Algorithm Your child will learn the traditional algorithm in 5th grade. In 4th grade, we are still working on building number sense and understanding the concept of multiplication.

Multiplication Where do we start? In 4th grade, we begin with multiples of 10, 100, and 1,000.

Multiplication Next, we practice estimating answers.

Multiplication Next, we find the actual answers to multiplication problems using base 10 blocks. 1,000 block 100 flat 10 rod 1 unit or cube

Multiplication Students physically build the multiplication problem using base ten blocks. For example: 3 x 42 Students think “3 groups of 42”

Multiplication 3 x 42 How many blocks are there all together? Count the rods (10’s). Count the units (1’s). Write the equation. Write the equation. 6 x 1 = 6 12 x 10 = 120 5 1 6 2 12 9 10 11 1 2 3 4 6 7 8 5 3 4

Multiplication 3 x 42 Next, count how many blocks are in all the groups. Count the rods (10’s). Count the units (1’s). Write the equation. Write the equation. 12 x 10 = 120 6 x 1 = 6 Add the partial products.

Multiplication 3 x 42 Next, count how many blocks are in all the groups. Count the rods (10’s). Count the units (1’s). Write the equation. Write the equation. 12 x 10 = 6 x 1 = + 126 Record the product. = 126

Multiplication Your turn! Using the base ten blocks, build this problem: 3 x 52

Multiplication Next, students show the multiplication problem by drawing the base ten blocks. . 100 flat 10 rod unit/cube For example, 3 x 42 would look like this:

Multiplication The next step is to show the multiplication problem by drawing base ten blocks in an array (columns and rows). 3 x 42 First, draw the frame for the problem.

Multiplication 3 x 42 = 126 Next, fill in the area of the frame. Now, count the 10 rods and units in the area. 12 x 10 = 120 6 x 1 = 6 120 + 6 = 126 Add the partial products. 3 x 42 = 126

Multiplication Here’s another way to show an array.

Multiplication Here’s another example of an array.

Multiplication In the next stage, students use the same array frame.  Now they’ll draw a rectangle to represent the area. 40 + 2 3 x 40 = 120 3 x 2 = 6 3 Next, write the equations in each area. Add the partial products: 120 + 6 = 126. 3 x 42 = 126

Multiplication Your turn! 5 x 34 = 170 30 + 4 5 5 x 30 = 150 30 + 4 5 5 x 4 = 20 5 x 30 = 150 Next, write the equations in each area. Add the partial products: 150 + 20 = 170.

Multiplication Here’s another example to show the area model.

Multiplication Some students are able to multiply without using a model.  They can picture the model in their minds, and write the corresponding partial product equations.  60 + 8 7 60 x 7 = 420 8 x 7 = 56 420 + 56 = 476

Multiplication 2 digit x 2 digit Start by estimating the answer.   

Multiplication Students find the actual answer to a 2 digit x 2 digit problem using the area model.  Example:   29 x 43 40 + 3 20 + 9 20 x 3 = 60 20 x 40 = 800 9 x 3 = 27 9 x 40 = 360 Add the partial products: 800 + 60 = 860 360 + 27 = 387 1,247 29 x 43 = 1,247

Multiplication Your turn! 34 x 15

Division We begin with dividing multiples of 10, 100, and 1,000.

Division Next, students estimate the answer.

Division Next, students build the problem using base ten blocks.

Division Your turn! 47 ÷ 4 = 11 R3

Division Students can use an area model.

Division Here’s the last method! Partial Quotients (aka 7 Frame)

Division Your turn! Use base ten blocks, the area model, or the partial quotients 7 frame. 365 ÷ 5

Any Questions? Please feel free to ask for help any time. We can always be reached by email. Thank you so much for attending our Math Night. We hope it will be helpful to you and your child. If you have any suggestions to improve our presentation, please send them our way!