Question

if a number is divisible by both 3 and 7,it is also divisible by 21. why

Answer 1

Answer:

because 21 is a multiple of both 3 as well as 7

Answer 2

If a number is divisible by both 3 and 7 then it is always divisible by 21 because If Any number is divisible by two numbers a and b then number is always divisible by LCM ( a , b)

"If Any number is divisible by two numbers a and b then number is always

divisible by LCM ( a , b)"

LCM  - Least common multiplier of given numbers is the least number which is perfectly divisible by given numbers.

LCM = product of each factor  of highest power

Given that Number if Divisible by both 3 and 7

3 and 7 are prime numbers

Hence LCM ( 3 , 7 ) = 21

Hence , Number if always divisible by 21

Because If Any number is divisible by two numbers a and b then number is always divisible by LCM ( a , b)

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