Test: HCF & LCM- 1 - Class 5 MCQ

A number’s greatest factor is always the number itself.
So, the greatest factor of 50 is 50.

• LCM is divisible by HCF.
• Hence, 8 cannot be the HCF  because 84 is not divisible by 8.
• Hence , 8 is the correct option.

Factors of 28 → 1, 2, 4, 7, 14, 28

Factors of 35 → 1, 5, 7, 35

Common → 1, 7

Highest = 7.

• The Prime numbers between the numbers 1 to 100 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.
• Here, we can see that the total count of prime numbers is 25.

• The HCF of two coprime numbers is always 1.
• For example, 5 and 9 are coprime numbers, there, HCF (5, 9) = 1.

• The product of 2 co-prime numbers is equal to their LCM.
• Hence, if one number is 16 other one is 
• 

• Let the other number be x
• Product of two numbers = HCF × LCM 
•  x × 36 = 6 × 144
•  
•  Hence, the other number is x = 24

Factors of 16 → 1, 2, 4, 8, 16

Factors of 24 → 1, 2, 3, 4, 6, 8, 12, 24

Factors of 36 → 1, 2, 3, 4, 6, 9, 12, 18, 36

Common factors → 1, 2, 4.

The highest is 4.

Formula: HCF × LCM = Product of numbers.
So, 6 × LCM = 180 
LCM = 180 ÷ 6 = 30.

• In number theory, Co-prime numbers are those numbers if the only positive factor that divides them is 1.
  Here,
• Option A: (16,18) Factors that divide both of them are 1,2.
• Option B: (11,48) Factor that divides both of them is 1.
• Option C: (8,23) Factor that divides both of them is 1.
• In reference to above definition both b and c are co-prime numbers.