Use 10 to subtract.

Use 10 to subtract.

In Kindergarten and 1st grade you learned that TEN AND SOME MORE made a teen number.

You can use that strategy to help you subtract!

Let's go!

- Miss G

10 + 7 = 17

Listen to the audio, please! Thank you!

Poll

Have you ever seen this kind of question before? 10 + __ = 17

• Yes!

• No

Multiple Choice

What is the number sentence 10 + __ = 17 asking you to answer?

• How many tens there are

• What addend is missing in the blank spot

• What the sum of 10 and 17 is

• I don't know

Did you answer "what addend is missing in the blank spot"?

If so, you were correct! When we see a problem that begins with 10 + and then has a blank space, we need to use the sum shown to figure out what addend is missing.

In kindergarten or 1st grade you might count by 1s to find out what addend is missing. In 2nd grade we want to just KNOW how much it is!

In 2nd grade we want you to understand it is just 7 without having to count all the jumps in your head or on paper!

Listen to the audio!

10 + 7 = 17

so...we can use this to subtract.

17 - 7 = 10

Poll

Do you understand me so far?

• Yes!

• Kind of

• No. :(

Now let's use that same fact. 10 + 7 = 17

We know that is true. Which means that 17 - 7 = 10.

BUT WHAT IF THE SUBTRACTION PROBLEM WAS 17 - 9 = ?

No worries! We can use what we know!

17 - 9 ? How can we use 17 - 7 = 10 to help us solve 17 - 9?

Easy! The difference between 7 and 9 is 2. That means we have to subtract 2 more from the fact we already know

Now you try!

First I will ask the 10 and some more or teen and some less question.

THEN I will ask a question that uses that fact!

YOU CAN DO IT!

Great Job! You did it!

See you on Friday!

- Miss G