To Multiply or Divide, that is the question!

Now that we know how to do complicated math like multiplying or dividing we tend to get stuck doing one skill or the other. Sometimes it’s time to multiply and sometimes it’s time to divide, but it’s not always one way or the other!

One tip is to notice the numbers given in the problem:

If the problem gives you a big number to be split apart by a little number- then it’s time to divide!

If the problem gives you two numbers to put together- then it’s time to multiply!

So, try these problems. Are we multiplying or dividing?

I have three friends and each friend has 11 freckles on her face! How many freckles do my friends have altogether?

I have 33 pencils and 3 friends. I want to split the pencils between my friends equally. How many pencils would each friend get?

Here’s our math talk problem. Visit the blog tomorrow to see who solved it perfectly!

I have 32 cookies and 4 friends. If each of my friends are super hungry, how many cookies will they get?

Division Stories

Division problems can be tricky when you first try to attack them! Coming up with a story to go with your problem can help you understand what the problem is asking you to do. For example the problem  10/5= x can look confusing. But when you write a story for it, it is easy! Look at this division problem below from Mrs. Harris’ class.

Here is another problem to consider:

18/3 = x

To solve this problem I can come up with a story to help me think about splitting 18 three different ways. Here is my story:

I have three boxes to carry 18 cupcakes in to school. If I want each box to contain an equal number of cupcakes, how many cupcakes will end up in each box?

Now I can draw out pictures of the boxes and split the cupcakes into each one. After I split up the cupcakes equally, I see that I have six cupcakes in each box. 18/3 = 6

It’s your turn! Write a division problem for this equation:

24/4 = x

For our Math Blog Center this week, write division problems for the following equations. Draw pictures, and solve the problems. Remember to write your problems out on the center paper and leave a comment as well!

12/6 = x

24/3 = x

30/5 = x

Division Math Talk

Yesterday, we had another great math talk! Our mathematician talked us through a challenging division problem. She showed us how she used reverse subtraction, or subtracting backwards, to solve her problem.

Here was our problem: Francisco had 30 soccer balls and 5 sports bags. If he split them equally, how many balls would fit in each bag.

First our mathematician subtracted 5’s backwards from 30. She wrote the equation 30 – 5 = 25, then 25 – 5 = 20, and so on all the way down to 5 – 5 = 0. Next, she counted up how many times she subtracted five of the soccer balls from the original 30. She figured out that 30 can be split by 5, 6 times! So Francisco can put 6 soccer balls into each of the 5 sports bags. 30/5 = 6.

Math Talk Day 2

Math Talk Day 2 3

Expanded Subtraction!

Why are these kids so happy? They’ve learned the secret of expanded subtraction! Sometimes you have to expand a number to see what is going on inside of it! Expanded subtraction helps you reorganize a number to use it the way you need to.

expanded subtraction 4

expanded subtraction

expanded subtraction 5

expanded subtraction 2

expanded subtraction 3

 Expanded subtraction also works great when it’s time to borrow from the tens column!

Your turn: Use this strategy on the following problems. Leave a comment with your solutions!

1. 343 – 248 =

2. 555 – 109 =

3. 882 – 334 =

4. 912 – 207 =