**What is a hundreds number chart?**

A **hundreds number chart** is a 10-by-10 grid with the numbers from one to one hundred printed in the squares, just as shown below. A hundreds chart can be customized depending on who will use it and how it will be used.

A hundreds number chart is very helpful in building fluency with numbers from 1 to 100. The numbers can be read from left to right in rows of 10, starting from the top left corner with the number 1, all the way down to 100 in the bottom right corner.

If you look at the hundreds number chart horizontally, you can see that the numbers increase by 1 as you move from left to right of each row. If you look at it vertically, you will notice that the numbers increase by 10 as you move down a square in each column.

For example, if you look at the column shaded in blue above, you can observe that the numbers are increasing by 10 each time (10, 20, 30, 40 and so forth). Each number ends in a 0, but the tens digit increases by 1 each time.

**Uses of Hundreds Number Chart**

Using a hundreds number chart will provide us a framework for thinking about the base ten number system. It will also allow us to build a mental model of the mathematical structure of our number system. Hundreds charts enable us to explore mathematical concepts such as number patterns, place value, skip counting, addition, subtraction, and multiples of a number. The hundreds number chart is one of the most valuable models to help us develop initial understandings of place value and the base-ten number system.

### Develop counting skills and number sense

This one may sound obvious, but a hundreds number chart is a brilliant tool for those learning to count and building their number sense .

For example, when we ask a young child to count numbers from 1 to 100 , we may find that they lose their pace, skip over a number, or repeat numbers along the way. But, if they use a hundreds number chart to practice counting, they can follow along with the numbers on the chart as they are counting. Nevertheless, a hundreds chart is basically a long number line from 1 to 100 packed in a handy and compressed 10 x 10 grid.

In addition, using a hundreds chart in counting enables them to see the number as they say it. This means that they start to recognize and connect the number name to the numerals or symbols that represent a certain number.

A number chart can also be used in practicing counting backward by simply reading the numbers from right to left instead of left to right.

### Skip counting

A hundreds number chart is a really useful tool when children begin with skip counting.

For example, let us use the hundreds number chart to show skip counting by 5. Use a blank hundreds chart and shade the grid of every 5th number on a chart just like below.

Using a hundreds chart can help us introduce skip counting to a child that will enable them to really see the idea behind it. For example, they can notice that we are just skipping over 4 numbers and then shading in the 5th one and then repeating this process over and over as we skip count.

It is also a great idea to take time to look at the patterns that emerge in the hundreds number chart when doing skip counting. The patterns can emerge from the numbers that we are shading and also from the patterns that the shaded squares create.

For example, in the skip counting by 5s table above, we can see that the shaded squares create two shaded columns and the numbers that have been shaded in either end in a 5 or a 0.

Now, let us try to skip count by twos.

Here we can notice that it produces more columns of shaded squares. The pattern that we can see here is that we shade in all the even numbers (numbers ending in 0, 2, 4, 6, and 8) and that alternate columns are shaded.

Lastly, let us also try to skip count by 3. This is an exciting one because the numbers always produce such a great pattern on the chart. Below you can see that the diagonal stripes emerge as you skip count by 3.

### Adding and subtracting numbers

Another practical use of the hundreds number chart is the addition and subtraction of numbers from 1 to 100. Even though that sounds like it might be difficult, but it is straightforward.

For example, let us use the hundreds chart to add 34 and 30.

To start, find the number 34. Next, let us add 30. We know that every time we move a square below a number, we are adding 10. We also know that 30 is equal to 3 groups of 10. So this means, we can move 3 squares down the chart from 34 just like below.

And we land on is 64, so this tells us that 34 + 30 = 63.

Let us try another example, say find the sum of 35 and 12.

Start by finding 35 on the hundreds number chart. Since we are adding 13, we can add the 10 first and then the 2 ones.

So, starting at 35, move **down** one square to add 10. Then move along the row 2 squares **to the right**.

And we land on 47. Thus, 35 + 12 = 47.

#### Now let us try subtraction using a hundreds number chart.

Once you already know how to do addition using a hundreds number chart, subtracting numbers is basically the same as addition, but we do it in a reverse process.

For example, let us find the result of 77 – 23.

We start by finding 77 on the hundreds number chart and since we are subtracting 23, we subtract 20 first and then 3 ones.

To subtract 20, move **up** the chart 2 squares. Then subtract the 3 ones by moving 3 squares to the **left**.

And we finish on 54. Thus, 77 – 23 = 54.

Once children learn to understand how the numbers in the hundreds number chart work, like the addition and subtraction of 10s and 1s, it will be easy for them to solve addition and subtraction questions involving 2-digit numbers.

**Activities Using a Hundreds Number Chart**

**Finding the mystery number**

This activity is fun to do because who does not love figuring out a mystery?

Using a hundreds number chart, guess the mystery number by working out with given clues. For example:

1^{st} Clue: The mystery number has two digits.

2^{nd} Clue: The mystery number is less than 15.

3^{rd} Clue: You can only set down on the mystery number by skip counting by 3’s.

What is the mystery number?

The answer is 12.

**Discovering Patterns**

When you first introduce this activity to students it is important that you start with familiar numbers. For example, ask the students to place clear chips on the following numbers in the hundreds chart: 5, 10, 15, 20, 25, 30. Then ask them to discuss the patterns they have noticed in the hundreds number chart with a partner.

Some students may notice that the numbers with a clear chip ends with either 0 or 5. They may also observe that they are five numbers apart. When the students are done with the discussion of patterns with their partners, choose a few of them to share their ideas with the class.

Then, provide another opportunity for students to place the clear chips on familiar numbers like 35, 40, 45, 50, 55, and 60, and follow the same process as above.

Below are some guide questions you may want to consider asking the students as they discussed about number patterns:

- What patterns did you notice?
- How did you see these patterns? Can you prove it by explaining it to us?
- What do you think will happen if I change the first number from 35 to 34? Will the pattern change, or will it remain the same? Can you still skip count by the same amount?
- Did you notice any patterns with the digits in the numbers? What are they?

To finish off, allow the students to create their own patterns that skip count by 5.

On other days, you may want to allot time for students to look at less conventional patterns that skip count by 5’s such as 32, 37, 42, 47, 52, and 57. Make use of the same guide questions from above to facilitate meaningful discussions.

Remember that the most important element in this activity is to provide your students ample time to discuss the patterns that they discovered.

Now apply the same process when skip counting by other numbers such as by 10’s.

**Hundreds Charts Puzzle**

This activity involves cutting up a hundreds number chart into sections and letting the students put the puzzle pieces back together.

To start, pick a hundreds number chart and cut it into 5 to 8 different sections. Then, present the different chart puzzle pieces to the students and tell them that you need their help in putting the hundreds number chart back together. You may allow the students to work with a partner to put the pieces of the hundred number chart puzzle back together.

Below are some guide questions you may want to consider asking as the students put the puzzle pieces back together.

- Why did you place that section next to that other section?
- How can you say that this is correct?
- What did you learn about numbers as you worked out this activity?

**Race to 100**

This activity will allow students to understand the number sequence using the hundreds number chart.

Tell the students that they will be working in pairs for the Race to 100 activity. Provide each player with their own hundreds number chart and a game piece such as a counting chip. Each pair should also have one number cube or dice. Each player will place their game piece on the smallest number of their hundreds chart which is 1. They will take turns in rolling the number cube and moving their game piece based on the outcome of the rolled number cube. For example, if the student rolls a 3, they will advance 3 spaces on the hundreds chart. The first student to land on 100 will be declared the winner of the Race to 100 activity.

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