Octal Number System
The number with base eight is called octal number. We can generate these numbers with the combination of 0, 1, 2 3, 4, 5, 6, 7. This note provides an information about Octal Number System and its conversions.
Summary
The number with base eight is called octal number. We can generate these numbers with the combination of 0, 1, 2 3, 4, 5, 6, 7. This note provides an information about Octal Number System and its conversions.
Things to Remember
- The number with base eight is called octal number. It is represented by Q or O.
- When decimal number is repetitively divided by eight and remainders are arranged in the form of octal numbers,then decimal number are converted into octal.
- Each octal is multiplied by its weighted position. The sum of all products is known as decimal form of octal.
- The three digit format of binary digits is used for octal to binary conversions or vice versa.
MCQs
No MCQs found.
Subjective Questions
Q1:
The frequency distribution table for 231 people of a village classified according to their ages is as follows:
Age Group (year) | No.of people |
0 - 5 | 18 |
5 - 10 | 15 |
10 - 15 | 14 |
15 - 20 | 31 |
20 - 25 | 33 |
25 - 30 | 60 |
30 - 35 | 23 |
35 - 40 | 20 |
40 - 45 | 12 |
45 - 50 | 5 |
Type: Short Difficulty: Easy
Q2:
The total materials expenditure of Rs. 9800 for a student to study in higher education in Kathmandu is given in the pie chart below. Answer the following questions on the basis of the pie chart.
(i) how much is spent for books?
(ii). How much is the expenditure for house rent and food more than that of education?
Type: Short Difficulty: Easy
Q3:
The different materials in a bundle of 100 meters of cloths weighing 25 kg were found as shown in th pie chart given below :
Answers the following questions on the basis of the pie chart :
(i). What is the weight of cotton in the bundle of cloth ?
(ii). Which of two raw materials have equal weight ? What is the weight of those items ?
(iii). How many times is the weight of Nylon heavier than cotton ?What is the weight of Nylom ?
(iv). What is the percentage of polyster ?
Type: Short Difficulty: Easy
Q4:
The blood groups of 900 patients who came to Bir Hospital , Ktahmandu being injured in accidents throughout as follows.
Draw a pie chart on the basis of the given data. (There are 4 types of human blood i.e , A , B , AB and O.)
Types Of blood | A | B | AB | O |
Percentage | 40% | 10% | 5% | 45% |
Type: Short Difficulty: Easy
Q5:
The percentage distribution of different elements in the body of a man of 60 kg is given below. Express the weight in percentage ond represent them in a pie.
Element | Muscles | Bones | Blood | Fats | Others |
Percentage | 45% | 18% | 12% | 20% | 5% |
Type: Short Difficulty: Easy
Q6:
The daily schedule of class 9 students is as follows : Convert these data into percentage and then represent them in a pie chart :
Work | School | Sports | Homework | Food | Misc | Sleeping |
Time (hour) | 7 | 2 | 3 | 1 \(\frac{1}{2}\) | 2 \(\frac{1}{2}\) | 8 |
Type: Long Difficulty: Easy
Q7:
A survey of 360 household of a municipality was conducted regarding the use of fuel for cooking. The data were found as follows :
Fuel Type | wood | electricity | gas | Kerosene |
Percentage | 12.5% | 22.5% | 25% | 40% |
Represent this data in a pie chart .
Type: Long Difficulty: Easy
Q8:
Draw the histogram for the following data given in the following frequency table.
Number | Frequency |
0 - 20 10 -20 20 - 30 30 - 40 40 - 50 |
2 3 4 3 1 |
Type: Short Difficulty: Easy
Q9:
Draw the histogram for the following data given in the following frequency table
Number | Frequency |
20 - 30 30 - 40 40 - 50 50 - 60 60 - 70 |
1 4 3 2 3 |
Type: Short Difficulty: Easy
Q10:
Draw the histogram for the following data given in the following frequency table.
Number | Frequency |
5 - 10 10 - 15 15 - 20 20 - 25 25 - 30 30 - 35 |
3 2 4 1 5 2 |
Type: Short Difficulty: Easy
Q11:
Draw the histogram for the following data given in the following frequency table
Number | Frequency |
5 - 15 15 - 25 25 - 35 35 - 45 45 - 55 55 -65 |
2 4 3 3 2 4 |
Type: Short Difficulty: Easy
Q12:
Construct the histogram for each of the following data with equal size of class intervals and make a less than type cumulative frequency table for each of them. Then draw the ogive :
Class | Frequency |
10 -15 15 -20 20 - 25 25 - 30 30 - 35 |
2 4 3 2 3 |
Type: Long Difficulty: Easy
Q13:
Construct the histogram for the data with equal size of class intervals and make a less than type cumulative frequency table for each of them. Then draw the ogive :
Class | Frequency |
12 -15 15 - 18 18 - 21 21 - 24 24 - 27 27 - 30 |
2 4 3 6 4 1 |
Type: Long Difficulty: Easy
Q14:
The pulse rate per minute of 34 students of class IX was measured and found to be as follows:
61 56 72 65 67 59 68 82 60 66 52 59 73 68
66 61 51 59 84 68 79 75 68 58 71 62 57 53
74 70 66 71 54
Represent the above data by frequency distribution table and cumulative frequency table by taking the class intervals 55 - 60, 60 - 65,.....
Class interval |
Tally Marks |
Frequency |
50 – 55 |
//// |
4 |
55 – 60 |
//// / |
6 |
60 – 65 |
//// |
5 |
65 – 70 |
//// //// |
9 |
70 – 75 |
//// / |
6 |
75 – 80 |
/ / |
2 |
80 – 85 |
// |
2 |
|
|
Total = 34 |
Type: Short Difficulty: Easy
Q15:
The marks obtained in a unit test of 25 full marks by 23 students of class IX are as follows :
17 15 12 5 18 24 20 10 14
20 23 17 22 21 14 9 13
21 24 20 25 16
Represent the above data in a frequency distribution table by classifying them into the class 0 - 5 , 5 - 10. . . ,
Type: Short Difficulty: Easy
Q16:
The votes secured by three candidates A , B and C from the total polling of 12000 for one seat of the parliament member in the general parliamentary election in the year 2056 are presented in the following pie chart :
Study the pie chart and answer the following questions :
(i). How many votes did B get ?
(ii). Who secured the highest vote ?
Type: Short Difficulty: Easy
Q17:
Find the arithmetic mean of given discrete data.
Wages(rs.) | 120 | 150 | 175 | 200 | 225 | 300 |
No. of workers | 12 | 17 | 11 | 13 | 4 | 3 |
Type: Short Difficulty: Easy
Q18:
Find the arithmetic mean.
Marks Obtained | 32 | 40 | 45 | 50 | 55 | 65 | 82 |
No. of students | 9 | 12 | 17 | 13 | 11 | 5 | 4 |
Type: Short Difficulty: Easy
Q19:
The mean of the given data is 17 , what is the value of x ?
Marks Obtained | 5 | 10 | 15 | 20 | `25 | 30 |
No. of students | 2 | 5 | 10 | x | 4 | 2 |
Type: Short Difficulty: Easy
Q20:
If the mean of the given data below is 5 . 6, find the value of p:
x | 2 | 4 | 6 | 8 | 10 |
f | 7 | 4 | p | 5 | 4 |
Type: Short Difficulty: Easy
Videos
Statistics - Mean, Median, Mode
Statistics intro: Mean, median, and mode | Data and statistics
Statistics: The average | Descriptive statistics | Probability and Statistics | Khan Academy

Octal Number System
The number with base eight is called octal number. It is represented by Q or O. We can generate these numbers with the combination of 0, 1, 2 3, 4, 5, 6, 7. We can represent these numbers wit suffix eight. Eg (5432)8
Weighted value
85 | 84 | 83 | 82 | 81 | 80 |
32768 | 4096 | 512 | 64 | 8 | 1 |
Conversions from Decimal to Octal
Decimal number is repetitively divided by eight and remainders are arranged in the form of octal numbers.
Example
Convert (240)10into octal.
8 | 240 | 0 |
8 | 30 | 6 |
3 |
(240)10= (360)8
Convert (356)10into octal.
8 | 356 | 4 |
8 | 44 | 4 |
4 |
(365)10=(444)8
Conversions from Octal to Decimal.
Each octal is multiplied by its weighted position. The sum of all products is known as decimal form of octal.
Example
Convert the octal numbers into decimal
- (340)8= 3 x 82+ 4 x 81+ 0 x 80=192 + 32 + 0 = (224)10
- (175)8= 1 x82+7 x 81+ 5 x80= (125)10
Octal to Binary and Binary to Octal Conversions
The three digit format of binary digits is used for octal to binary conversions or vice versa.
Octal to Binary
3-bits binary numbers are written for each octal digit.
Example
Convert (56)8 (octal) into binary.
Algorithm:
- Convert each octal digit into binary and make three digits grouping.
5= 101
6= 110
Now our equivalent binary number is (56)8=(101110)2
Convert (64102)8 into Binary number.
6= 110
4= 100
1= 001
0= 000
2= 010
Now our equivalent binary number is (64102)8= (110100001000010)2
Binary to Octal
The binary numbers are broken into 3-bits section from last bit and convert into octal equivalent of each binary section. Table shows the decimal, octal and equivalent binary bits.
Decimal | Octal | Binary |
0 | 0 | 000 |
1 | 1 | 001 |
2 | 2 | 010 |
3 | 3 | 011 |
4 | 4 | 100 |
5 | 5 | 101 |
6 | 6 | 110 |
7 | 7 | 111 |
Example
Convert (10011)2 into octal number.
Algorithm
- make 3-bits grouping from last bit.
010 011 - convert each group into decimal numbers.
010 = 2
011 = 3
= (23)8
Convert (1011010011)2 into octal number.
001 011 010 011
001= 1
011= 3
010= 2
011= 3
= (1323)8
Octal to Hexadecimal
Algorithm
- Convert octal into binary.
- make groups of 4-bits from last bit.
- convert each group into decimal numbers.
Example
1. (34765)8into Hexadecimal number.
- Convert into binary
3= 011, 4= 100, 7=111, 6= 110, 5=101
(011100111110101)2 - Make a four digits group from the last bit of the binary number.
0011 1001 1111 0101 (Add 0 before the group to make four digit)
3 9 15 5 (Convert into equivalent decimal numbers)
=(39F5)16Where F= 15
Lesson
Computer Number System
Subject
Computer Science
Grade
Grade 10
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