3rd Grade Math

Place Value

Unit 2


What is Place Value?

  1. The different digits of base 10 numbers have different value based on their place.

  2. For example, the in the number 324, the 4 is in the ones place, the 2 is in the tens place, and the 3 is in the hundreds place.

  3. This means that the 4 in the ones place stands for 4 ones, or 4. The 2 in the tens place stands for 2 tens, or 20. Finally, the 3 in the hundred place stands for 3 hundreds, or 300. These add up to a total of 300 + 20 + 4 = 324.

Place Value Names

Each position in a number has a name to describe that position! For example, the position directly to the left of a decimal or furthest to the right of a whole number (a number without decimals) is called the "ones place".

Take a look at the picture to the left to see the names of each position in a number!

Rounding!

Rounding is a method of estimation (guessing) that pretends that numbers are closer to slightly larger or smaller versions of themselves, such as multiples of ten or 100. For example, 599 is very close to 600, so it may be rounded to 600 (which is a multiple of 100).

Read the picture to the left to learn more! Then, take a look at the examples below for more practice!

Rounding to the nearest tens place!

1287

  • Look at the last digit of the number! Is it greater than 5?

  • Yes! Because 7 is greater than 5, we must round the number UP to the nearest 10!

  • What is the nearest multiple of 10 from 87? 90!

  • Our final answer for rounding 1287 to the nearest tens place is ... 1290!


Rounding to the nearest hundreds place!

530

  • Look at the digits in the tens place of the number! Since we are rounding to the hundreds place, we must use50 as a reference! Are the numbers greater than 50?

  • No! Because 30 is less than 50, we must round DOWN to the nearest 100. What is the nearest multiple of 100? 500!

  • Our final answer for rounding 530 to the nearest hundreds place is 500!

Comparing Numbers!

How do we tell if some numbers are bigger than others?

Use these symbols to tell that some numbers are larger than others!

Less Than! Equal To! Greater Than!

< = >

If a number is less than another number (comes before it in the number line), use this symbol!

<

For example, 5 is lower than/less than 10, so you would write it as

5 < 10

If a number is equal to (the same as) another number, use this symbol!

=

For example, 5 is equal to (the same as) 5, so you would write it as

5 = 5

If a number is greater than another number (comes after it in the number line), then use this symbol!

>

For example, 10 is greater than (more than) 5, so you would write it as

10 > 5

Want to see some more examples of comparing numbers?

Use the drop down arrow for more practice!

  1. 78 ___ 45

78 > 45


  1. 23 ___ 16

23 > 16


  1. 9 ___ 27

9 < 27


Write the numbers from greatest to least

  1. 178, 79, 390

390, 178, 79

Write the numbers from least to greatest

  1. 145, 67, 180

67, 145, 180

This graph is called a pictograph b

Reading Graphs and Data

Graphs are displays of information that make it easier for us to see how much or how little of something we have!

  1. In the graph to the left, each book represents 5 books.

  2. This means Nancy had 5 x 5 = 25 books.

  3. This means Juan had 8 x 5 = 40 books.

  4. So, this means Juan has 15 more books than Nancy.

  1. Different objects of different sizes have different measurements which can be taken by a ruler.

  2. For example, an object that is 5 1/2 inches long is longer than (greater than) an objects is a 3 inches long.