Session Three
Welcome to the third section of MTH140, Number bases. In this session you will learn about the place values in the binary system as well as how to convert binary numbers in standard notation to expanded notation.
Begin this session by watching the video tape. If you have purchased a textbook, follow along in your book. If you are using the Internet version, follow along on the webpage. If you have any difficulties, contact your instructor. After the explanation of place values, turn off the video player and try to work the practice problems. Once you have worked the problems, check your answers in the answer key or click on the Answer Key Links.
Section Three
Place Values In The Binary Number System
The binary number system is used in computer applications. This system is based on two digits. The digits 0 and 1 are used in the binary number system. When counting, once all of the digits have been used, a combination of digits must then be used. As digits are added, place value increases. For example, the "number" after 1 is 10. Two digits are used in the number 10; the digit placement in the number tells us the "size" of the number. The digits are used sequentially when we build numbers. The number after 11 is 100. This is because the digit on the far right has reached the maximum of value of 1 and we must begin to "reuse" values in this position.
The following numbers are the first ten numbers that we could use to count in the binary system. Zero (0) has the same value of "nothing" that we use in the decimal system. The next number would be 1, then 10, 11, 100, 101, 110, 111, 1000, 1001, and 1010. A number that contains digits other than zero or one cannot be a binary number. For example, 456 cannot be a binary number. The number 1001 can be a binary number since it only contains the digits one and zero. Often times these numbers are written with a subscript to tell the reader that the numbers are binary numbers. They could be written as 12, 102, 112, 1002, 1012, 1102, 1112, 10002, 10012, and 10102 to avoid confusion.
3.1 ~ Converting from Standard Notation to Expanded Notation
Each value of a number is determined by the position of each digit in the number. The "place" of the digit has a name. In the number 1012, we refer to the position where the 1 is located on the far right hand side as the "units" place or the "two to the zero power" place. The 0 is in the "twos" place or the "two to the first power" place. The 1 on the far left is in the "fours" place or "two to the second power" place. Each additional place would be "two" to the next successive power.
The number 1012 is in standard binary notation. If we looked at the number 1012 and wrote it in a different way, we might put the information in a table such as the one shown in Table 1 ~ 3.1.
Table 1 ~ 3.1
| Digit |
x |
Power of Two |
= |
Value |
|
1 |
x |
20 |
= |
12 |
|
0 |
x |
21 |
= |
002 |
|
1 |
x |
22 |
= |
1002 |
|
Total Value |
1012 |
Notice that numbers in the second column are all powers of two. If we wrote the number 101 without using the chart, it would be written as:
1 x 1 + 0 x 2 + 1 x 4
Another way of writing this would be:
1 x 20 + 0 x 21 + 1 x 22
We call this an expanded form.
Since the number 2 in binary notation is represented by 102, we could write the expanded notation in another way. It could be written as:
1 x 100 + 0 x 101 + 1 x 102
or putting in the subscript, it could be written as
1 x 1020 + 0 x 1021 + 1 x 1022
Notice the similarities between what has been written above and the manner in which decimal numbers are written in expanded notation. They are the same except for the subscript.
Notice that numbers in the second column are all powers of two. If we wrote the number 101 without using the chart, it would be written as:
1 x 1 + 0 x 2 + 1 x 4
Another way of writing this would be:
1 x 20 + 0 x 21 + 1 x 22
We call this an expanded form.
Since the number 2 in binary notation is represented by 102, we could write the expanded notation in another way. It could be written as:
1 x 100 + 0 x 101 + 1 x 102
or putting in the subscript, it could be written as
1 x 1020 + 0 x 1021 + 1 x 1022
Notice the similarities between what has been written above and the manner in which decimal numbers are written in expanded notation. They are the same except for the subscript.
Figure 3.1.1
Place Values for Binary Number 1012
1 0 1
| | |__________1020
| | _________________1021
|________________________1022
Example: Convert 110012 to expanded notation
Solution: First, identify the value of each digit. The first digit on the right, the digit 1 is in the units or the two to the zero power place; the next digit 0, is in the twos or two to the first power place; the next digit 0, is in the fours or two to the second power place; the next digit 1 is in the eights or two to the third power place; the final digit 1 is in the sixteens or two to the fourth power place.
Table 3.1.2
| Digit |
x |
Power of Two |
= |
Value |
|
1 |
x |
20 or 12 |
= |
12 |
|
0 |
x |
21 or 102 |
= |
002 |
|
0 |
x |
22 or 1002 |
= |
0002 |
|
1 |
x |
23 or 10002 |
= |
10002 |
|
1 |
x |
24 or 100002 |
= |
100002 |
|
Total Value |
110012 |
If we wrote the number without using the chart, the number would be
1 x 20 + 0 x 21 + 0 x 22 + 1 x 23 + 1 x 24
The number is now in an expanded form. Since the number 2 in binary notation is represented by 102, we could write the expanded form in another way. It could be written as:
1 x 100 + 0 x 101 + 0 x 102 + 1 x 103 + 1 x 104
or putting in the subscript, it could be written as:
1 x 1020 + 0 x 1021 + 0 x 1022 + 1 x 1023 + 1 x 1024
Now the number is in expanded notation.
Figure 2 ~ 3.1
Place Values for Binary Number 100112
1 0 0 1 1
| | | | | __________1020
| | | |_________________1021
| | | ________________________1022
| |_______________________________1023
|_______________________________________1024
3.1 ~Practice Problems
Directions: Turn off your VCR. Change the following numbers from standard notation to expanded notation. When you have finished working the problems, check your answers in the back of your book or click here to view the Answer Key. Turn on your VCR to view the solutions to the practice problems worked out on the board by a teacher.
- 11112
- 1000112
- 102
- 12
- 101110112
3.1 ~ Homework Problems
Directions: Turn off your VCR. Convert the following numbers from standard notation to expanded notation. Keep your work in a notebook to be turned into your instructor at the conclusion of the course. When you have finished working the problems, check your answers in the back of the book or click here to view the Answer Key. If you have any questions, contact your instructor.
- 1002
- 101112
- 11101012
- 1112
- 1101101102
- 1102
- 111011112
- 1011112
- 1000001112
- 110112
Turn on your VCR and continue with this section. If you have purchased a textbook, follow along in your book. If you are using the Internet version, follow along on the webpage. If you have any difficulties, contact your instructor. After the explanation of converting binary numbers from expanded notation to standard notation, turn off the video player and try to work the practice problems. Once you have worked the problems, check your answers in the answer key listed in the back of your book or click on the Answer Key Links located at the end of every section.
3.2 ~ Converting from Expanded Notation to Standard Notation
We can change numbers that have been written in expanded notation to standard notation by reversing the process. Suppose we have the notation
1 x 20 + 1 x 21 + 1 x 22 + 0 x 23 + 1 x 24
Recalling the information in Figure 1 ~ 3.1 and extending the idea, we could make a table for the powers of two in binary notation.
Table 1 ~ 3.2 ~ Table of Powers of 2 vs. Binary Notation
|
Power of 2 |
Binary Notation |
|
20 |
12 |
|
21 |
102 |
|
22 |
1002 |
|
23 |
10002 |
|
24 |
100002 |
|
25 |
1000002 |
|
26 |
10000002 |
|
27 |
100000002 |
|
28 |
1000000002 |
|
29 |
10000000002 |
|
210 |
100000000002 |
We might think of our number in another way as
1 x 1020 + 1 x 1021 + 1 x 1022 + 0 x 1023 + 1 x 1024
Table 3.2.2
| Digit |
x |
Multiple of Two |
= |
Value |
|
1 |
x |
1020 (or 12) |
= |
12 |
|
1 |
x |
1021 (or 102) |
= |
102 |
|
1 |
x |
1022 (or 1002) |
= |
1002 |
|
0 |
x |
1023 (or 10002) |
= |
00002 |
|
1 |
x |
1024 (or 100002) |
= |
100002 |
|
Total Value |
101112 |
Adding these values together, we get 101112 in standard notation.
Example: Convert 1 x 1020 + 1 x 1021 + 0 x 1022 + 1 x 1023 + 0 x 1024 + 1 x 1025 to standard notation.
Solution: If we follow the rules of order of operations, we must first evaluate the powers of two.
1 x 12 + 1 x 102 + 0 x 1002 + 1 x 10002 + 0 x 100002 + 1 x 1000002
Next, we perform the multiplication.
12 + 102 + 0002 + 10002 + 000002 + 1000002
Finally, we add the numbers together to obtain the sum:
1010112
which is the number in standard form.
3.2 ~ Practice Problems
Directions: Turn off your VCR. Change the following numbers from expanded notation to standard notation. Check your answers in the Answer Key. Turn on your VCR to view the solutions to the problems below.
- 1 x 1020 + 1 x 1021 + 1 x 1022
- 1 x 1020 + 0 x 1021 + 0 x 1022 + 1 x 1023 + 1 x 1024
- 1 x 1020 + 1 x 1021 + 1 x 1022 + 1 x 1024
- 0 x 1020 + 1 x 1021
- 1 x 1020
- 6. 1 x 1021 + 1 x 1022 + 0 x 1023 + 0 x 1024 + 1 x 1025 + 1 x 1026
3.2 ~ Homework Problems
Directions: Turn off your VCR. Convert the following numbers from expanded notation to standard notation. Check your answers in the Answer Key.
- 1 x 1020 + 1 x 1021 + 0 x 1022 + 1 x 1023
- 1 x 1020 + 1 x 1021 + 1 x 1023 + 1 x 1025
- 1 x 1021
- 1 x 1020 + 0 x 1021 + 0 x 1022 + 0 x 1023 + 1 x 1024
- 1 x 1020
- 1 x 1020 + 1 x 1021 + 1 x 1022 + 0 x 1023 + 0 x 1024 + 1 x 1025 + 1 x 1026
- 1 x 1020 + 1 x 1021 + 1 x 1024
- 1 x 1022 + 1 x 1023 + 1 x 1024 + 1 x 1025
- 1 x 1023 + 1 x 1024
- 1 x 1027
Turn on your VCR and continue with this section. If you have purchased a textbook, follow along in your book. If you are using the Internet version, follow along on the webpage. If you have any difficulties, contact your instructor. After the explanation of adding binary numbers, turn off the video player and try to work the practice problems. Once you have worked the problems, check your answers in the answer key listed in the back of your book or click on the Answer Key Links located at the end of every section.
3.3 ~ Adding Numbers in Binary Notation
Addition in base two is very similar to addition in base ten. The first step is learning the addition facts for base two. Since there are only two digits used in the binary system, there are only three different mathematics facts that we must know. When we add any two digits together and their sum is less than the decimal number two, the sum is the same in both bases. The first two facts in the binary system are the same as in the decimal system, that is 0 + 0 = 0 and 0 + 1 = 1. (Of course the reflexive property addition holds so that 1 + 0 = 1.) We know that the equivalent of the decimal number 2 is the binary value 102. Consequently, 1 + 1 = 10 in base two. As with addition base ten, a table can provide easy reference to the addition facts in base two. We can refer to the addition table for base two depicted in Table 1 ~ 3.1 as we work our examples.
Table 1 ~ 3.1 Addition Table Base Two (Binary System)