What will be the LCM of (26) and (39)?
Correct answer: A
Step 1: (26=2\times13) and (39=3\times13). Step 2: For LCM, take (2), (3), and (13). Step 3: (2\times3\times13=78), so the answer is (78).
View question detailsMathematics
HCF and LCM using prime factorisation
अभाज्य गुणनखंडन द्वारा महत्तम समापवर्तक और लघुत्तम समापवर्त्य
In this Class 10 Mathematics topic from Real Numbers, students learn to find the HCF and LCM of two or more numbers through prime factorisation. They break each number into prime factors, compare the resulting powers, and select the appropriate common factors: the lowest powers for HCF and the highest powers for LCM. The topic also develops accuracy in writing factor trees, simplifies comparison between methods, and helps students apply these concepts to numerical and everyday problem-solving situations.
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Easy · Level 11 · real-numbers,lcm,prime-factorisation
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- (78)
- (117)
- (156)
- (234)
Easy · Level 11 · real-numbers,hcf,word-problem
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- (8)
- (12)
- (16)
- (24)
Easy · Level 11 · real-numbers,hcf,word-problem
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- (7)
- (14)
- (21)
- (28)
Easy · Level 11 · real-numbers,lcm,word-problem
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- (30)
- (45)
- (60)
- (90)
Easy · Level 11 · real-numbers,lcm,word-problem
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- (24)
- (32)
- (48)
- (96)
Easy · Level 11 · real-numbers,hcf,application
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- (6)
- (12)
- (18)
- (24)
Easy · Level 11 · real-numbers,hcf,application
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- (9)
- (18)
- (27)
- (36)
Easy · Level 11 · real-numbers,hcf,prime-powers
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- (5)
- (10)
- (25)
- (50)
Easy · Level 11 · real-numbers,lcm,prime-powers
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- (150)
- (200)
- (300)
- (400)
Easy · Level 11 · real-numbers,hcf,prime-powers
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- (7)
- (14)
- (21)
- (49)
Easy · Level 11 · real-numbers,lcm,prime-powers
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- (294)
- (441)
- (588)
- (882)
Easy · Level 11 · real-numbers,hcf,given-factorisation
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- (18)
- (36)
- (54)
- (72)
Easy · Level 11 · real-numbers,lcm,given-factorisation
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- (270)
- (360)
- (540)
- (1080)
Easy · Level 11 · real-numbers,hcf,three-numbers
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- (9)
- (18)
- (27)
- (54)
Easy · Level 11 · real-numbers,lcm,three-numbers
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- (81)
- (108)
- (162)
- (324)
Easy · Level 11 · real-numbers,hcf,prime-factorisation
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- (12)
- (24)
- (36)
- (48)
Easy · Level 11 · real-numbers,lcm,prime-factorisation
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- (240)
- (360)
- (720)
- (1440)
Easy · Level 11 · real-numbers,prime-factorisation,basic
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- (180)
- (240)
- (360)
- (720)
Easy · Level 11 · real-numbers,prime-factorisation,basic
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- (600)
- (900)
- (1200)
- (1800)
Easy · Level 11 · real-numbers,lcm,concept
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- Smaller power of common factors
- Highest power of all prime factors
- Only common factors
- Only the smallest number
A class has (32) boys and (48) girls. What can be the maximum number of equal groups?
Correct answer: C
Step 1: For maximum equal groups, find the HCF. Step 2: (32=2^5) and (48=2^4\times3), so HCF (=2^4=16). Step 3: In equal distribution questions, the word maximum usually points to HCF.
View question detailsA shopkeeper wants to pack (42) apples and (56) oranges in equal bags. What is the maximum number of bags possible?
Correct answer: B
Step 1: For the maximum number of equal bags, find the HCF of (42) and (56). Step 2: (42=2\times3\times7) and (56=2^3\times7), so HCF (=2\times7=14). Step 3: In packing questions with equal and maximum, use HCF.
View question detailsTwo bells ring at intervals of (15) minutes and (20) minutes. After how many minutes will they ring together again?
Correct answer: C
Step 1: The next common ringing time is the LCM of the intervals. Step 2: (15=3\times5) and (20=2^2\times5), so LCM (=2^2\times3\times5=60). Step 3: For repeated time events, use LCM.
View question detailsThree indicators glow at intervals of (8), (12), and (16) seconds. After how many seconds will they glow together again?
Correct answer: C
Step 1: The next common glowing time is the LCM of (8), (12), and (16). Step 2: (8=2^3), (12=2^2\times3), and (16=2^4). Step 3: (2^4\times3=48), so the answer is (48) seconds.
View question detailsRopes of (60) m and (84) m are to be cut into equal pieces of maximum length. What will be the length of each piece?
Correct answer: B
Step 1: For equal pieces of maximum length, find the HCF. Step 2: (60=2^2\times3\times5) and (84=2^2\times3\times7), so HCF (=2^2\times3=12). Step 3: In cutting questions, maximum equal length is found by HCF.
View question detailsStrips of (54) m and (90) m are to be cut into equal pieces of maximum length. What will be the length of each piece?
Correct answer: B
Step 1: For maximum equal length, find the HCF of (54) and (90). Step 2: (54=2\times3^3) and (90=2\times3^2\times5), so HCF (=2\times3^2=18). Step 3: When lengths are cut equally, use HCF.
View question detailsWhat is the HCF of (75) and (100)?
Correct answer: C
Step 1: (75=3\times5^2) and (100=2^2\times5^2). Step 2: The common prime factor is (5), and the smaller power is (5^2). Step 3: (5^2=25), so the HCF is (25).
View question detailsWhat is the LCM of (75) and (100)?
Correct answer: C
Step 1: (75=3\times5^2) and (100=2^2\times5^2). Step 2: The highest powers are (2^2), (3), and (5^2). Step 3: (4\times3\times25=300), so the LCM is (300).
View question detailsWhat is the HCF of (98) and (147)?
Correct answer: D
Step 1: (98=2\times7^2) and (147=3\times7^2). Step 2: The common prime factor is (7), and the smaller power is (7^2). Step 3: (7^2=49), so the HCF is (49).
View question detailsWhat is the LCM of (98) and (147)?
Correct answer: A
Step 1: (98=2\times7^2) and (147=3\times7^2). Step 2: The LCM includes (2), (3), and (7^2). Step 3: (2\times3\times49=294), so the answer is (294).
View question detailsIf (108=2^2\times3^3) and (180=2^2\times3^2\times5), what is their HCF?
Correct answer: B
Step 1: The common prime factors are (2) and (3). Step 2: The smaller powers are (2^2) and (3^2). Step 3: (4\times9=36), so the HCF is (36).
View question detailsIf (108=2^2\times3^3) and (180=2^2\times3^2\times5), what is their LCM?
Correct answer: C
Step 1: For LCM, take the highest powers of all prime factors. Step 2: The highest powers are (2^2), (3^3), and (5). Step 3: (4\times27\times5=540), so the answer is (540).
View question detailsWhat is the HCF of (27), (54), and (81)?
Correct answer: C
Step 1: (27=3^3), (54=2\times3^3), and (81=3^4). Step 2: The common prime factor is (3), and the smallest power is (3^3). Step 3: (3^3=27), so the HCF is (27).
View question detailsWhat is the LCM of (27), (54), and (81)?
Correct answer: C
Step 1: (27=3^3), (54=2\times3^3), and (81=3^4). Step 2: The highest powers are (2) and (3^4). Step 3: (2\times81=162), so the LCM is (162).
View question detailsWhat is the HCF of (72) and (120)?
Correct answer: B
Step 1: (72=2^3\times3^2) and (120=2^3\times3\times5). Step 2: The smaller powers of common factors are (2^3) and (3). Step 3: (8\times3=24), so the HCF is (24).
View question detailsWhat is the LCM of (72) and (120)?
Correct answer: B
Step 1: (72=2^3\times3^2) and (120=2^3\times3\times5). Step 2: The highest powers are (2^3), (3^2), and (5). Step 3: (8\times9\times5=360), so the LCM is (360).
View question detailsThe prime factorisation of a number is (2^3\times3^2\times5). What is the number?
Correct answer: C
Step 1: First evaluate the powers: (2^3=8) and (3^2=9). Step 2: Now (8\times9\times5=360). Step 3: While forming a number from factorisation, simplify powers first and then multiply.
View question detailsThe prime factorisation of a number is (2^4\times3\times5^2). What is the number?
Correct answer: C
Step 1: (2^4=16) and (5^2=25). Step 2: The number is (16\times3\times25=1200). Step 3: In long multiplication, pair easy numbers first, such as (16\times25=400).
View question detailsWhile finding LCM by prime factorisation, which power is taken?
Correct answer: B
Step 1: LCM is the smallest number divisible by all the given numbers. Step 2: Therefore, the highest powers of all prime factors are taken. Step 3: Remember the rule: all factors with highest powers for LCM.
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