100 LearnersLast updated on May 26th, 2025
Factors of 1991
Factors are the numbers that divide any given number evenly without remainder. In daily life, we use factors for tasks like sharing items equally, arranging things, etc. In this topic, we will learn about the factors of 1991, how they are used in real life, and tips to learn them quickly.
What are the Factors of 1991?
The numbers that divide 1991 evenly are known as factors of 1991.
A factor of 1991 is a number that divides the number without remainder.
The factors of 1991 are 1, 11, 181, and 1991.
Negative factors of 1991: -1, -11, -181, and -1991.
Prime factors of 1991: 11 and 181.
Prime factorization of 1991: 11 × 181.
The sum of factors of 1991: 1 + 11 + 181 + 1991 = 2184
How to Find Factors of 1991?
Factors can be found using different methods. Mentioned below are some commonly used methods:
- Finding factors using multiplication
- Finding factors using the division method
- Prime factors and Prime factorization
Finding Factors Using Multiplication
To find factors using multiplication, we need to identify the pairs of numbers that are multiplied to give 1991. Identifying the numbers which are multiplied to get the number 1991 is the multiplication method.
Step 1: Multiply 1991 by 1, 1991 × 1 = 1991.
Step 2: Check for other numbers that give 1991 after multiplying 11 × 181 = 1991
Therefore, the positive factor pairs of 1991 are: (1, 1991), (11, 181).
For every positive factor, there is a negative factor.
Finding Factors Using Division Method
Dividing the given numbers with whole numbers until the remainder becomes zero and listing out the numbers which result as whole numbers as factors. Factors can be calculated by following a simple division method
Step 1: Divide 1991 by 1, 1991 ÷ 1 = 1991.
Step 2: Continue dividing 1991 by the numbers until the remainder becomes 0.
1991 ÷ 1 = 1991
1991 ÷ 11 = 181
Therefore, the factors of 1991 are: 1, 11, 181, and 1991.
Prime Factors and Prime Factorization
The factors can be found by dividing it with prime numbers. We can find the prime factors using the following methods:
- Using prime factorization
- Using a factor tree
Using Prime Factorization: In this process, prime factors of 1991 divide the number to break it down in the multiplication form of prime factors till the remainder becomes 1.
1991 ÷ 11 = 181
181 ÷ 181 = 1
The prime factors of 1991 are 11 and 181.
The prime factorization of 1991 is: 11 × 181.
Factor Tree
The factor tree is a graphical representation of breaking down any number into prime factors. The following step shows
Step 1: Firstly, 1991 is divided by 11 to get 181.
Step 2: 181 is a prime number and cannot be divided further.
So, the prime factorization of 1991 is: 11 × 181.
Factor Pairs: Two numbers that are multiplied to give a specific number are called factor pairs. Both positive and negative factors constitute factor pairs.
Positive factor pairs of 1991: (1, 1991), (11, 181).
Negative factor pairs of 1991: (-1, -1991), (-11, -181).
Common Mistakes and How to Avoid Them in Factors of 1991
Mistakes are common while finding factors. We can identify and correct those mistakes using the following common mistakes and the ways to avoid them.
Mistake 1
Forgetting the number itself and 1 is a factor
Children might forget to add the given number itself and 1 as a factor. The number itself and 1 are the factors for every number. Always remember to include 1 and the number itself.
For example, in factors of 1991, 1 and 1991 are also factors.
Factors of 1991 Examples
Problem 1
A concert hall has 1991 seats and tickets are sold in blocks of 11. How many blocks are there?
There are 181 blocks.
Explanation
To find the number of blocks, divide the total seats by the block size.
1991/11 = 181
Problem 2
A rectangular garden has a length of 11 meters and a total area of 1991 square meters. Find the width.
181 meters.
Explanation
To find the width of the garden, we use the formula,
Area = length × width
1991 = 11 × width
To find the value of width, divide 1991 by 11.
1991/11 = width
Width = 181.
Problem 3
A theater has 1991 seats arranged equally in 181 rows. How many seats are there in each row?
Each row has 11 seats.
Explanation
To find the number of seats in each row, divide the total seats by the number of rows.
1991/181 = 11
Problem 4
A school distributed 1991 pencils equally among 11 teachers. How many pencils did each teacher receive?
Each teacher received 181 pencils.
Explanation
Dividing the total pencils by the number of teachers gives the number of pencils per teacher.
1991/11 = 181
Problem 5
A library has 1991 books arranged in 11 equal piles. How many books are in each pile?
Each pile has 181 books.
Explanation
Divide total books by the number of piles.
1991/11 = 181
FAQs on Factors of 1991
1.What are the factors of 1991?
2.Mention the prime factors of 1991.
3.Is 1991 a multiple of 11?
4.Mention the factor pairs of 1991?
5.What is the square of 1991?
6.How can children in Vietnam use numbers in everyday life to understand Factors of 1991?
7.What are some fun ways kids in Vietnam can practice Factors of 1991 with numbers?
8.What role do numbers and Factors of 1991 play in helping children in Vietnam develop problem-solving skills?
9.How can families in Vietnam create number-rich environments to improve Factors of 1991 skills?
Important Glossaries for Factors of 1991
- Factors: The numbers that divide the given number without leaving a remainder are called factors. For example, the factors of 1991 are 1, 11, 181, and 1991.
- Prime factors: The factors which are prime numbers. For example, 11 and 181 are prime factors of 1991.
- Prime factorization: It is expressing a number as the product of its prime factors. For example, the prime factorization of 1991 is 11 × 181.
- Factor pairs: Two numbers in a pair that are multiplied to give the original number are called factor pairs. For example, the factor pairs of 1991 are (1, 1991) and (11, 181).
- Composite number: A number that has more than two factors. 1991 is a composite number because it has factors other than 1 and itself.
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About BrightChamps in Vietnam
Hiralee Lalitkumar Makwana
About the Author
Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.
Fun Fact
: She loves to read number jokes and games.
