Which is the prime factorisation of 108?
Step 1: Write (108=4\times27). Step 2: (4=2^2) and (27=3^3), so (108=2^2\times3^3). Step 3: 12 and 9 are composite, so they are not the final prime form.
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SubjectsMathematics
अंकगणित का मौलिक प्रमेय
In this Class 10 Mathematics topic from the chapter Real Numbers, students learn that every integer greater than 1 can be expressed as a product of prime numbers, and that this prime factorisation is unique apart from the order of the factors. They practise finding prime factors and use the theorem to understand and determine the HCF and LCM of numbers. The topic builds clear reasoning about the structure of whole numbers and supports later work with divisibility and number relationships.
TOPIC PRACTICE
Up to 25 questions from this page. Select your focus, then start.
Step 1: Write (108=4\times27). Step 2: (4=2^2) and (27=3^3), so (108=2^2\times3^3). Step 3: 12 and 9 are composite, so they are not the final prime form.
Step 1: A prime number must have exactly two positive factors. Step 2: 1 has only one positive factor, 1, so it is neither prime nor composite. Step 3: Treating 1 as prime is a common mistake.
Step 1: Look at the given form (96=2^5\times3). Step 2: The exponent written on 2 is 5. Step 3: While reading powers, identify the base and exponent separately.
Step 1: Write (126=2\times63). Step 2: (63=9\times7=3^2\times7), so (126=2\times3^2\times7). Step 3: 6 and 21 are composite, so they are not final answers.
Step 1: For two numbers, product (=) HCF (\times) LCM. Step 2: (5\times60=300). Step 3: Use this formula when the question is about two numbers.
Step 1: Write 81 as (9\times9). Step 2: Each 9 is (3^2), so (81=3^4). Step 3: 9 is composite, so (9^2) is not prime factorisation.
Step 1: Write (150=15\times10). Step 2: (15=3\times5) and (10=2\times5), so the distinct prime factors are 2, 3, and 5. Step 3: Write a repeated factor only once in a distinct list.
Step 1: The common prime factors are 2 and 3. Step 2: The smaller powers are (2^1) and (3^1), so the HCF is (2\times3=6). Step 3: Take smaller powers for HCF.
Step 1: For LCM, take higher powers. Step 2: The higher power of (2) is 3 and of (3) is 2, so (2^3\times3^2=72). Step 3: LCM includes the highest powers of all prime factors.
Step 1: Write (200=8\times25). Step 2: (8=2^3) and (25=5^2), so (200=2^3\times5^2). Step 3: 20 and 10 are composite, so they are not prime factorisation.
Step 1: Multiply the given prime factors. Step 2: (2\times3\times7=42), so the number is 42. Step 3: To get the number from factorisation, multiply all factors.
Step 1: Find (2^4=16). Step 2: (16\times3=48), so the number is 48. Step 3: First evaluate the power, then multiply.
Step 1: In prime factorisation, all factors must be prime. Step 2: In (4\times3), 4 is not prime, so this is not prime factorisation. Step 3: If a composite factor appears, factorise it further.
Step 1: Write (132=12\times11). Step 2: (12=2^2\times3) and 11 is prime, so (132=2^2\times3\times11). Step 3: Do not leave 12 in the final form because it is composite.
Step 1: (14=2\times7) and (25=5^2). Step 2: They have no common prime factor, so they are co-prime. Step 3: Co-prime numbers have HCF 1.
Step 1: Write (225=15\times15). Step 2: Each 15 is (3\times5), so (225=3^2\times5^2). Step 3: 15 is composite, so (15\times15) is not the final prime form.
Step 1: The common prime factors are 2 and 5. Step 2: The smaller powers are (2^2) and (5^1), so HCF is (4\times5=20). Step 3: For HCF, take smaller powers of common factors only.
Step 1: For LCM, take the highest powers of all prime factors. Step 2: (2^3\times3\times5=8\times3\times5=120). Step 3: In LCM, include prime factors that appear in either number.
Step 1: A number divisible by both 2 and 3 is also divisible by 6. Step 2: 36 is even and its digit sum is 9, so it is also divisible by 3. Step 3: Divisibility checks help in prime factorisation.
Step 1: Find (2^2=4) and (5^2=25). Step 2: (4\times3\times25=300). Step 3: In questions with powers, simplify the powers first.
Step 1: This theorem is about writing positive integers greater than 1 as products of primes. Step 2: So it discusses numbers greater than 1. Step 3: Do not include 1 in the usual prime factorisation statement.
Step 1: Write (210=21\times10). Step 2: (21=3\times7) and (10=2\times5), so (210=2\times3\times5\times7). Step 3: In the final form, all factors must be prime.
Step 1: Multiply the given prime factors. Step 2: (3\times5\times7=105), so the number is 105. Step 3: To get the original number from prime factorisation, multiply all factors.
Step 1: Write (180=18\times10). Step 2: (18=2\times3^2) and (10=2\times5), so (180=2^2\times3^2\times5). Step 3: Combine repeated prime factors using powers.
Step 1: Co-prime numbers have HCF 1. Step 2: For two numbers, product (=) HCF (\times) LCM. Step 3: Therefore, the LCM of co-prime numbers is equal to their product.
QUIZ COMPLETE