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2 <p>Last updated on<strong>September 19, 2025</strong></p>

3 <p>The GCF is the largest number that can divide two or more numbers without leaving any remainder. GCF is used to share the items equally, to group or arrange items and schedule events. In this topic, we will learn about the GCF of 28 and 20.</p>

4 <h2>What is the GCF of 28 and 20?</h2>

5 <p>The<a>greatest common factor</a>of 28 and 20 is 4. The largest<a>divisor</a>of two or more<a>numbers</a>is called the GCF of the number. If two numbers are co-prime, they have no common factors other than 1, so their GCF is 1.</p>

6 <p>The GCF of two numbers cannot be negative because divisors are always positive.</p>

7 <h2>How to find the GCF of 28 and 20?</h2>

8 <p>To find the GCF of 28 and 20, a few methods are described below </p>

9 <ul><li>Listing Factors </li>

10 <li>Prime Factorization </li>

11 <li>Long Division Method / by Euclidean Algorithm</li>

12 </ul><h2>GCF of 28 and 20 by Using Listing of Factors</h2>

13 <p>Steps to find the GCF of 28 and 20 using the listing of<a>factors</a></p>

14 <p><strong>Step 1:</strong>Firstly, list the factors of each number</p>

15 <p>Factors of 28 = 1, 2, 4, 7, 14, 28.</p>

16 <p>Factors of 20 = 1, 2, 4, 5, 10, 20.</p>

17 <p><strong>Step 2:</strong>Now, identify the<a>common factors</a>of them Common factors of 28 and 20: 1, 2, 4.</p>

18 <p><strong>Step 3:</strong>Choose the largest factor The largest factor that both numbers have is 4.</p>

19 <p>The GCF of 28 and 20 is 4.</p>

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22 <h2>GCF of 28 and 20 Using Prime Factorization</h2>

21 <h2>GCF of 28 and 20 Using Prime Factorization</h2>

23 <p>To find the GCF of 28 and 20 using Prime Factorization Method, follow these steps:</p>

22 <p>To find the GCF of 28 and 20 using Prime Factorization Method, follow these steps:</p>

24 <p><strong>Step 1:</strong>Find the<a>prime factors</a>of each number</p>

23 <p><strong>Step 1:</strong>Find the<a>prime factors</a>of each number</p>

25 <p>Prime Factors of 28: 28 = 2 x 2 x 7 = 2² x 7</p>

24 <p>Prime Factors of 28: 28 = 2 x 2 x 7 = 2² x 7</p>

26 <p>Prime Factors of 20: 20 = 2 x 2 x 5 = 2² x 5</p>

25 <p>Prime Factors of 20: 20 = 2 x 2 x 5 = 2² x 5</p>

27 <p><strong>Step 2:</strong>Now, identify the common prime factors The common prime factors are: 2 x 2 = 2²</p>

26 <p><strong>Step 2:</strong>Now, identify the common prime factors The common prime factors are: 2 x 2 = 2²</p>

28 <p><strong>Step 3:</strong>Multiply the common prime factors 2² = 4.</p>

27 <p><strong>Step 3:</strong>Multiply the common prime factors 2² = 4.</p>

29 <p>The Greatest Common Factor of 28 and 20 is 4.</p>

28 <p>The Greatest Common Factor of 28 and 20 is 4.</p>

30 <h2>GCF of 28 and 20 Using Division Method or Euclidean Algorithm Method</h2>

29 <h2>GCF of 28 and 20 Using Division Method or Euclidean Algorithm Method</h2>

31 <p>Find the GCF of 28 and 20 using the<a>division</a>method or Euclidean Algorithm Method. Follow these steps:</p>

30 <p>Find the GCF of 28 and 20 using the<a>division</a>method or Euclidean Algorithm Method. Follow these steps:</p>

32 <p><strong>Step 1:</strong>First, divide the larger number by the smaller number</p>

31 <p><strong>Step 1:</strong>First, divide the larger number by the smaller number</p>

33 <p>Here, divide 28 by 20 28 ÷ 20 = 1 (<a>quotient</a>),</p>

32 <p>Here, divide 28 by 20 28 ÷ 20 = 1 (<a>quotient</a>),</p>

34 <p>The<a>remainder</a>is calculated as 28 - (20×1) = 8</p>

33 <p>The<a>remainder</a>is calculated as 28 - (20×1) = 8</p>

35 <p>The remainder is 8, not zero, so continue the process</p>

34 <p>The remainder is 8, not zero, so continue the process</p>

36 <p><strong>Step 2:</strong>Now divide the previous divisor (20) by the previous remainder (8)</p>

35 <p><strong>Step 2:</strong>Now divide the previous divisor (20) by the previous remainder (8)</p>

37 <p>Divide 20 by 8 20 ÷ 8 = 2 (quotient), remainder = 20 - (8×2) = 4</p>

36 <p>Divide 20 by 8 20 ÷ 8 = 2 (quotient), remainder = 20 - (8×2) = 4</p>

38 <p><strong>Step 3:</strong>Now divide the previous divisor (8) by the previous remainder (4)</p>

37 <p><strong>Step 3:</strong>Now divide the previous divisor (8) by the previous remainder (4)</p>

39 <p>Divide 8 by 4 8 ÷ 4 = 2 (quotient), remainder = 8 - (4×2) = 0</p>

38 <p>Divide 8 by 4 8 ÷ 4 = 2 (quotient), remainder = 8 - (4×2) = 0</p>

40 <p>The remainder is zero, the divisor will become the GCF.</p>

39 <p>The remainder is zero, the divisor will become the GCF.</p>

41 <p>The GCF of 28 and 20 is 4.</p>

40 <p>The GCF of 28 and 20 is 4.</p>

42 <h2>Common Mistakes and How to Avoid Them in GCF of 28 and 20</h2>

41 <h2>Common Mistakes and How to Avoid Them in GCF of 28 and 20</h2>

43 <p>Finding GCF of 28 and 20 looks simple, but students often make mistakes while calculating the GCF. Here are some common mistakes to be avoided by the students.</p>

42 <p>Finding GCF of 28 and 20 looks simple, but students often make mistakes while calculating the GCF. Here are some common mistakes to be avoided by the students.</p>

44 <h3>Problem 1</h3>

43 <h3>Problem 1</h3>

45 <p>A teacher has 28 apples and 20 oranges. She wants to group them into equal sets, with the largest number of items in each group. How many items will be in each group?</p>

44 <p>A teacher has 28 apples and 20 oranges. She wants to group them into equal sets, with the largest number of items in each group. How many items will be in each group?</p>

46 <p>Okay, lets begin</p>

45 <p>Okay, lets begin</p>

47 <p>We should find GCF of 28 and 20 GCF of 28 and 20 2² = 4.</p>

46 <p>We should find GCF of 28 and 20 GCF of 28 and 20 2² = 4.</p>

48 <p>There are 4 equal groups 28 ÷ 4 = 7 20 ÷ 4 = 5</p>

47 <p>There are 4 equal groups 28 ÷ 4 = 7 20 ÷ 4 = 5</p>

49 <p>There will be 4 groups, and each group gets 7 apples and 5 oranges.</p>

48 <p>There will be 4 groups, and each group gets 7 apples and 5 oranges.</p>

50 <h3>Explanation</h3>

49 <h3>Explanation</h3>

51 <p>As the GCF of 28 and 20 is 4, the teacher can make 4 groups.</p>

50 <p>As the GCF of 28 and 20 is 4, the teacher can make 4 groups.</p>

52 <p>Now divide 28 and 20 by 4.</p>

51 <p>Now divide 28 and 20 by 4.</p>

53 <p>Each group gets 7 apples and 5 oranges.</p>

52 <p>Each group gets 7 apples and 5 oranges.</p>

54 <p>Well explained 👍</p>

53 <p>Well explained 👍</p>

55 <h3>Problem 2</h3>

54 <h3>Problem 2</h3>

56 <p>A school has 28 red chairs and 20 blue chairs. They want to arrange them in rows with the same number of chairs in each row, using the largest possible number of chairs per row. How many chairs will be in each row?</p>

55 <p>A school has 28 red chairs and 20 blue chairs. They want to arrange them in rows with the same number of chairs in each row, using the largest possible number of chairs per row. How many chairs will be in each row?</p>

57 <p>Okay, lets begin</p>

56 <p>Okay, lets begin</p>

58 <p>GCF of 28 and 20 2² = 4.</p>

57 <p>GCF of 28 and 20 2² = 4.</p>

59 <p>So each row will have 4 chairs.</p>

58 <p>So each row will have 4 chairs.</p>

60 <h3>Explanation</h3>

59 <h3>Explanation</h3>

61 <p>There are 28 red and 20 blue chairs. To find the total number of chairs in each row, we should find the GCF of 28 and 20.</p>

60 <p>There are 28 red and 20 blue chairs. To find the total number of chairs in each row, we should find the GCF of 28 and 20.</p>

62 <p>There will be 4 chairs in each row.</p>

61 <p>There will be 4 chairs in each row.</p>

63 <p>Well explained 👍</p>

62 <p>Well explained 👍</p>

64 <h3>Problem 3</h3>

63 <h3>Problem 3</h3>

65 <p>A tailor has 28 meters of red ribbon and 20 meters of blue ribbon. She wants to cut both ribbons into pieces of equal length, using the longest possible length. What should be the length of each piece?</p>

64 <p>A tailor has 28 meters of red ribbon and 20 meters of blue ribbon. She wants to cut both ribbons into pieces of equal length, using the longest possible length. What should be the length of each piece?</p>

66 <p>Okay, lets begin</p>

65 <p>Okay, lets begin</p>

67 <p>For calculating the longest equal length, we have to calculate the GCF of 28 and 20</p>

66 <p>For calculating the longest equal length, we have to calculate the GCF of 28 and 20</p>

68 <p>The GCF of 28 and 20 2² = 4.</p>

67 <p>The GCF of 28 and 20 2² = 4.</p>

69 <p>The ribbon is 4 meters long.</p>

68 <p>The ribbon is 4 meters long.</p>

70 <h3>Explanation</h3>

69 <h3>Explanation</h3>

71 <p>For calculating the longest length of the ribbon first we need to calculate the GCF of 28 and 20 which is 4.</p>

70 <p>For calculating the longest length of the ribbon first we need to calculate the GCF of 28 and 20 which is 4.</p>

72 <p>The length of each piece of the ribbon will be 4 meters.</p>

71 <p>The length of each piece of the ribbon will be 4 meters.</p>

73 <p>Well explained 👍</p>

72 <p>Well explained 👍</p>

74 <h3>Problem 4</h3>

73 <h3>Problem 4</h3>

75 <p>A carpenter has two wooden planks, one 28 cm long and the other 20 cm long. He wants to cut them into the longest possible equal pieces, without any wood left over. What should be the length of each piece?</p>

74 <p>A carpenter has two wooden planks, one 28 cm long and the other 20 cm long. He wants to cut them into the longest possible equal pieces, without any wood left over. What should be the length of each piece?</p>

76 <p>Okay, lets begin</p>

75 <p>Okay, lets begin</p>

77 <p>The carpenter needs the longest piece of wood GCF of 28 and 20 2² = 4.</p>

76 <p>The carpenter needs the longest piece of wood GCF of 28 and 20 2² = 4.</p>

78 <p>The longest length of each piece is 4 cm.</p>

77 <p>The longest length of each piece is 4 cm.</p>

79 <h3>Explanation</h3>

78 <h3>Explanation</h3>

80 <p>To find the longest length of each piece of the two wooden planks, 28 cm and 20 cm, respectively.</p>

79 <p>To find the longest length of each piece of the two wooden planks, 28 cm and 20 cm, respectively.</p>

81 <p>We have to find the GCF of 28 and 20, which is 4 cm.</p>

80 <p>We have to find the GCF of 28 and 20, which is 4 cm.</p>

82 <p>The longest length of each piece is 4 cm.</p>

81 <p>The longest length of each piece is 4 cm.</p>

83 <p>Well explained 👍</p>

82 <p>Well explained 👍</p>

84 <h2>FAQs on the Greatest Common Factor of 28 and 20</h2>

83 <h2>FAQs on the Greatest Common Factor of 28 and 20</h2>

85 <h3>1.What is the LCM of 28 and 20?</h3>

84 <h3>1.What is the LCM of 28 and 20?</h3>

86 <p>The LCM of 28 and 20 is 140.</p>

85 <p>The LCM of 28 and 20 is 140.</p>

87 <h3>2.Is 20 divisible by 2?</h3>

86 <h3>2.Is 20 divisible by 2?</h3>

88 <p>Yes, 20 is divisible by 2 because it is an even number.</p>

87 <p>Yes, 20 is divisible by 2 because it is an even number.</p>

89 <h3>3.What will be the GCF of any two prime numbers?</h3>

88 <h3>3.What will be the GCF of any two prime numbers?</h3>

90 <p>The common factor of<a>prime numbers</a>is 1 and the number itself. Since 1 is the only common factor of any two prime numbers, it is said to be the GCF of any two prime numbers.</p>

89 <p>The common factor of<a>prime numbers</a>is 1 and the number itself. Since 1 is the only common factor of any two prime numbers, it is said to be the GCF of any two prime numbers.</p>

91 <h3>4.What is the prime factorization of 28?</h3>

90 <h3>4.What is the prime factorization of 28?</h3>

92 <p>The prime factorization of 28 is 2² x 7.</p>

91 <p>The prime factorization of 28 is 2² x 7.</p>

93 <h3>5.Are 28 and 20 prime numbers?</h3>

92 <h3>5.Are 28 and 20 prime numbers?</h3>

94 <p>No, 28 and 20 are not prime numbers because both of them have more than two factors.</p>

93 <p>No, 28 and 20 are not prime numbers because both of them have more than two factors.</p>

95 <h2>Important Glossaries for GCF of 28 and 20</h2>

94 <h2>Important Glossaries for GCF of 28 and 20</h2>

96 <ul><li><strong>Factors:</strong>Factors are numbers that divide the target number completely. For example, the factors of 8 are 1, 2, 4, and 8.</li>

95 <ul><li><strong>Factors:</strong>Factors are numbers that divide the target number completely. For example, the factors of 8 are 1, 2, 4, and 8.</li>

97 </ul><ul><li><strong>Multiple:</strong>Multiples are the products we get by multiplying a given number by another. For example, the multiples of 5 are 5, 10, 15, 20, and so on.</li>

96 </ul><ul><li><strong>Multiple:</strong>Multiples are the products we get by multiplying a given number by another. For example, the multiples of 5 are 5, 10, 15, 20, and so on.</li>

98 </ul><ul><li><strong>Prime Factors:</strong>These are the factors of a number that are prime numbers and divide the given number completely. For example, the prime factors of 30 are 2, 3, and 5.</li>

97 </ul><ul><li><strong>Prime Factors:</strong>These are the factors of a number that are prime numbers and divide the given number completely. For example, the prime factors of 30 are 2, 3, and 5.</li>

99 </ul><ul><li><strong>Remainder:</strong>The value left after division when the number cannot be divided evenly. For example, when 15 is divided by 4, the remainder is 3 and the quotient is 3.</li>

98 </ul><ul><li><strong>Remainder:</strong>The value left after division when the number cannot be divided evenly. For example, when 15 is divided by 4, the remainder is 3 and the quotient is 3.</li>

100 </ul><ul><li><strong>LCM:</strong>The smallest common multiple of two or more numbers is termed LCM. For example, the LCM of 28 and 20 is 140.</li>

99 </ul><ul><li><strong>LCM:</strong>The smallest common multiple of two or more numbers is termed LCM. For example, the LCM of 28 and 20 is 140.</li>

101 </ul><p>What Are Numbers? 🔢 | Fun Explanation with 🎯 Real-Life Examples for Kids | ✨BrightCHAMPS Math</p>

100 </ul><p>What Are Numbers? 🔢 | Fun Explanation with 🎯 Real-Life Examples for Kids | ✨BrightCHAMPS Math</p>

102 <p>▶</p>

101 <p>▶</p>

103 <h2>Hiralee Lalitkumar Makwana</h2>

102 <h2>Hiralee Lalitkumar Makwana</h2>

104 <h3>About the Author</h3>

103 <h3>About the Author</h3>

105 <p>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.</p>

104 <p>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.</p>

106 <h3>Fun Fact</h3>

105 <h3>Fun Fact</h3>

107 <p>: She loves to read number jokes and games.</p>

106 <p>: She loves to read number jokes and games.</p>