Basic Math

LCM AND HCF|Question

LCM and HCF are given information about meaning of LCM and HCF , LCM HCF question, co prime numbers, Find HCf, Find LCM, Division Method, Prime factorization.



LCM (Least Common Multiple)

 Least common multiple (LCM) of two given number. In other word LCM of two or more number is a number is a number which is common multiple of the number is the smallest among them.


There are two method to finding the LCM.
  1. Prime Factorization
  2. Division method

Prime factorization method

It is the simplest way to solve lcm and hcf Aptitude question. You write the all the prime factor of given number then find  highest power of the prime factor.Which will be the LCM.

Division Method

  • The easiest method to find out the LCM in aptitude question.
  •  In this method first write down the given number in a row and strike out those numbers which are factors of any other number in the rest.
  • Write the factor on the left hand side which can divide maximum of the number.
  • Then multiply all the left side number and last end number then LCM is the answer.

HCF (Highest Common Factor)

Highest Common Factor (HCF) is the greatest number that divided both the given number or more numbers.


There are two method to find out the HCF
  1. Prime factorization method.
  2. Division method.

Prime Factorization Method

  • Write each number as product of its prime factor.
  • Multiply the factor with lowest powers which are common to all number .HCF is equal to the product of such factor.

Finding the more about basic math Speed Distance Time

Division Method:-

  • Divide the greater number by the smaller number.
  • Next ,divided the preceding divisor by the remainder . continue until you get zero as reminder. The last divisor is the required HCF.


  • If the product of two co-prime number is 117, their LCM is

               (a) 9                       (b) 13

               (c) 17                     (d) 117
  • LCM of 114 and 95 is 

               (a) 570                    (b) 950

               (c) 1140                  (d) 5700
  • Find the smallest number divided by 42, 98 and 70.

                (a) 1470                  (b) 1740

                (c) 1070                  (d) 980
  • Find the HCF of two co-prime number is

                 (a) 0                        (b) 1

                 (c) 2                        (d) 3
  • The  LCM of 12, 24, and 30 is

                 (a) 2                        (b) 30

                 (c) 60                      (d) 120
  • HCF of 8, 18, 24 is

                 (a) 2                         (b) 4

                 (c) 6                         (d) 8
  • The product of two numbers is 216 and their HCF is  3, then their LCM is

                 (a) 648                     (b) 219

                 (c) 213                     (d) 72
  • Find the greatest number which divides 36 and 48 completely.

                 (a) 10                        (b) 11

                 (c) 12                        (d) 13
  • The greatest number that will divided 1375 and 4935 exactly is

                  (a) 5                          (b) 15

                  (c) 1375                    (d) 4935
  • Five bells beginning together toll at interval , 4 s, 5 s, 7 s, 8 s and 10 s, respectively. After what  interval of time will they toll again together .

                 (a) 2 m 20 s                (b) 4 m 40 s

                 (c) 6 m 40 s                (d) 2 m 40 s 

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