Main content

# Add and subtract within 20: FAQ

Frequently asked questions about adding and subtracting within 20.

## How can we use place value blocks to help add and subtract?

We can use place value blocks to represent each number we want to add, and then combine them to find the total.

For example, if we want to add start color #0c7f99, 12, end color #0c7f99, plus, start color #ca337c, 6, end color #ca337c, we can start by drawing start color #0c7f99, 12, end color #0c7f99 blocks and then make a second group of place value blocks that has start color #ca337c, 6, end color #ca337c blocks. After we put them together, we will see there are 18 blocks.

For subtraction, we can use the blocks to represent the larger number, and then take away the appropriate number of blocks to find the difference.

For example, to subtract start color #0c7f99, 14, end color #0c7f99, minus, start color #ca337c, 8, end color #ca337c, we can draw a set of blocks that has start color #0c7f99, 14, end color #0c7f99 place value blocks. Then we can take away start color #ca337c, 8, end color #ca337c place value blocks from the start color #0c7f99, 14, end color #0c7f99 blocks. Now, there are 6 blocks lets.

## How can we use ten frames to help add and subtract?

Ten frames can be helpful for adding and subtracting because they allow us to visually see the numbers we're working with. To add using ten frames, we can fill in the frames with the numbers we want to add.

For example, if we want to add 8 and 4, we could fill in eight squares on one ten frame and four squares on another ten frame. By combining the two frames, we can see that the sum is 12.

To subtract using ten frames, we can fill in the frame with the larger number and then remove squares to represent the smaller number. For example, if we want to subtract 3 from 7, we would fill in seven squares on the ten frame and then remove three squares. This would leave us with four squares filled in, which represents the difference.

## How can we use number lines to help add and subtract?

We can use the number line to visually represent the two numbers being added or subtracted. For example, to solve 7, plus, 9, we can mark both 7 and 9 on the number line. Then we can see that adding the two numbers together will result in a sum that falls between the two, at 16.

To solve 12, minus, 4, mark 12 on the number line. Then we can subtract 4 to see that the jump ends at 8.

## How can we use arrays to help us add?

We can use arrays to represent repeated addition! For example, an array of 5 rows and 3 columns can be thought of as adding start color #0c7f99, 5, end color #0c7f99, start color #7854ab, start text, space, t, h, r, e, e, s, end text, end color #7854ab.

## Where do we use addition and subtraction in the real world?

We use addition and subtraction all the time! For example, we might use them when we're counting money, dividing up snacks, or measuring ingredients for a recipe.

## Want to join the conversation?

- How do you add 6+7 by using base 10 blocks?(8 votes)
- You can add 6 + 7 using base 10 blocks this way:

Imagine that you have 2 boxes, 1 with 6 balls and 1 with 7 balls. You need to put 3 bolls in the 2nd box to make 10 on that box. So, you take 3 from the 1st box and put them on the 2nd box.

(6) + (7) =

(3 + 3) + 7 =

(3) + (3 + 7) =

(3) + (10) =

(13)(15 votes)

- The answer of 90+90 is 180. This could also be 90x2.(15 votes)

- karskilaru if you dont know what to do just ask for help i can help u if u like its easy math i know how to do it afterall im in 5th grade. :)(12 votes)
- What is 7(x+4)-12(y+4)=13(4 votes)

- what is 1000000000+9000000?(5 votes)
- Equals 19000000000000000(6 votes)