Question

how to check answer in lcm
2,4,8,10

Answer 1

LCM of  numbers 2, 4, 8, 10

Split all numbers in to prime factors.
 
 2 = 2^1
4  = 2 * 2 = 2^2
8 = 2* 2 * 2  = 2^3
10 = 2^1 * 5^1

multiply all factors with maximum of their powers : 2^3 * 5^1  = 40

To check the correctness of LCM,  divide LCM by each number, you will find that LCm is divisible by each number.  
40/2  , 40/4,  40/8,  40/10  are integers.

Answer 2

First of all find out the factors of all the numbers. then find out the lowest common factor. if this matches with your answer then your ans is correct.