Download What is a number???

Math 25 – Chapter 1
Whole Numbers and the Place Value System
Fall 2011
This class is all about numbers, but like with all things you can't begin without really thinking about the basics.
With that the first question is the most essential and valuable question to start thinking about. To help answer this
question below are some other thought provoking questions to consider.
What is a number???
1. Think of some examples of when we use numbers and how we use numbers. Talk to some one sitting near
you about this for a few minutes:
2. What symbols do we normally use to represent numbers? Write them down. (Hint: There are ten of them).
3. What do we call those symbols?
4. How is it that from these ten symbols we can create an infinite number of numbers?
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Math 25 – Chapter 1
Whole Numbers and the Place Value System
Fall 2011
Hundred millions
Ten millions
Millions
Hundred thousands
Ten thousands
Thousands
Hundreds
Tens
Units or “ones”
The Place Value Chart
2
1
3,
4
5
6,
7
8
9
Example 1: What does the 2 represent in the following numbers?
45,123
789,987,254
12,456
216,456
Expanded Form
Example 2: Write the following numbers in expanded form.
5,120
458,105
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Math 25 – Chapter 1
Whole Numbers and the Place Value System
Fall 2011
Reading and Writing Numerals
Example 3: Read the following numbers out loud and write the numbers out in words (like on a check).
78
678
5,512
81,124
Example 4: Write the following written numbers using digits and place value (just write the numbers using
numbers).
Seven thousand, eight hundred forty-two
Thirty thousand, four hundred twenty-nine
Two million, one hundred forty-one thousand, six hundred thirty-one
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Math 25 – Chapter 1
Whole Numbers and the Place Value System
Fall 2011
Rounding Whole Numbers
Do you know the exact price of a Toyota Camry or a new Lenovo Tablet? When you don't know the exact price of
something what do you do?
To round a number to the nearest ten:
1.
2.
3.
4.
Look at the tens digit. This number will either stay the same or increase.
If the ones digit is 0, 1, 2, 3, or 4, then you leave the tens digit the same.
If the ones digit is 5, 6 ,7, 8, or 9, then you increase the tens digit.
In both cases you make the digits to the right of the tens digit all zeros.
Example 5: Round the number to the nearest ten.
348 
2,352 
45,985 
278 
298 
3,497 
NOTE: There is one special case, and that is if the digit you are rounding to is a 9. You then have to increase the
digit, but when you do that then you must also increase the digit to the left.
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Math 25 – Chapter 1
Whole Numbers and the Place Value System
Fall 2011
Fill in the blanks to the following set of instructions for rounding to the nearest hundred.
To round a number to the nearest hundred:
1. Look at the __________ digit. This number will either stay the same or increase.
2. If the _________ digit is 0, 1, 2, 3, or 4, then you leave the ___________ digit the same.
3. If the _________ digit is 5, 6 ,7, 8, or 9, then you increase the ___________ digit.
4. In both cases you make the digits to the right of the hundreds digit all zeros.
Example 6: Round the number to the nearest hundred.
45,763 
123,233 
156,655 
88,991 
Example 7: Round the number to the nearest thousand.
45,763 
123,233 
156,655 
88,991 
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Math 25 – Chapter 1 – Turn in Page
NAME:
1.
What are the digits we use to write all of our numbers with?
2.
What does the 3 represent in the following numbers?
43,258 
987,365 
3.
Write the following numbers in words.
239 
5,382 
23,341 
4.
Write the following numbers in expanded form.
6,783 =
34,289 =
5.
Round the number to the nearest hundred.
8,749 
23,555 
6.
Round the number to the nearest thousand.
34,569 
239,845 
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