LCM and HCF


  1. The H.C.F. and L.C.M. of two 2-digit numbers are 16 and 480 respectively. The numbers are :









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    Given that ,
    L.C.M. of the two 2-digit numbers = 480
    H.C.F. of the two 2-digit numbers = 16
    Hence, the numbers can be expressed as 16p and 16q, where p and q are prime to each other.
    As we know that ,
    First number × second number = H.C.F. × L.C.M.
    ⇒ 16p × 16q = 16 × 480

    ⇒ pq =
    16 × 480
    = 30
    16 × 16

    Correct Option: D

    Given that ,
    L.C.M. of the two 2-digit numbers = 480
    H.C.F. of the two 2-digit numbers = 16
    Hence, the numbers can be expressed as 16p and 16q, where p and q are prime to each other.
    As we know that ,
    First number × second number = H.C.F. × L.C.M.
    ⇒ 16p × 16q = 16 × 480

    ⇒ pq =
    16 × 480
    = 30
    16 × 16

    The possible pairs of p and q, satisfying the condition pq = 30 are :- (3, 10), (5, 6), (1, 30), (2, 15)
    Since the numbers are of 2-digits each.
    Hence, admissible pair is (5, 6)
    i.e. p = 5 and q = 6
    ∴ Numbers are : 16p = 16 × 5 = 80 and 16q = 16 × 6 = 96


  1. The HCF of two numbers 12906 and 14818 is 478. Their LCM is









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    Here , LCM = ? , HCF = 478 , First number = 12906, Second number = 14818
    With the help of the given formula ,
    Product of two numbers = HCF × LCM
    ⇒ 12906 × 14818 = LCM × 478

    Correct Option: A

    Here , LCM = ? , HCF = 478 , First number = 12906, Second number = 14818
    With the help of the given formula ,
    Product of two numbers = HCF × LCM
    ⇒ 12906 × 14818 = LCM × 478

    ⇒ LCM =
    12906 × 14818
    = 400086
    478



  1. The LCM of two numbers is 1920 and their HCF is 16. If one of the number is 128, find the other number.









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    Given ,LCM = 1920 , HCF = 16 , First number = 128 , Second number = ?
    As We know that ,
    First number × second number = LCM × HCF

    ∴ Second number =
    LCM × HCF
    First number

    Correct Option: B

    Given ,LCM = 1920 , HCF = 16 , First number = 128 , Second number = ?
    As We know that ,
    First number × second number = LCM × HCF

    ∴ Second number =
    LCM × HCF
    First number

    ∴ Second number =
    1920 × 16
    = 45
    240


  1. The HCF of two numbers is 16 and their LCM is 160. If one of the number is 32, then the other number is









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    Given ,LCM = 160 , HCF = 16 , First number = 32 , Second number = ?
    We know that,
    First number × Second number = LCM × HCF

    Correct Option: B

    Given ,LCM = 160 , HCF = 16 , First number = 32 , Second number = ?
    We know that,
    First number × Second number = LCM × HCF

    ⇒ Second number =
    16 × 160
    = 80
    32



  1. LCM of two numbers is 225 and their HCF is 5. If one number is 25, the other number will be:









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    Given , LCM = 225 , HCF = 5 , First Number = 25 , Second Number = ?
    We can find the Second Number with the help of given formula ,
    LCM × HCF = 1st Number× 2nd Number
    ⇒ 225 × 5 = 25 × 2nd Number

    Correct Option: C

    Given , LCM = 225 , HCF = 5 , First Number = 25 , Second Number = ?
    We can find the Second Number with the help of given formula ,
    LCM × HCF = 1st Number× 2nd Number
    ⇒ 225 × 5 = 25 × 2nd Number

    2nd Number =
    225 × 5
    = 45
    25