Question

32. If a number is divisible by both 3 and 7 then the number is also divisible by
a) 11
c) 21
d) all the abov
b) 4​

Answer 1

Answer:

The correct answer is 21

Step-by-step explanation:

Given,

A number is divisible by 3 and 7

Recall the concepts:

LCM of two numbers is defined as the least common multiple of both numbers.

Let 'P' be the number that is divisible by both 3 and 7. Since P is divisible by 3 and 7, the number is divisible by all the common multiples of 3 and 7 less than P

Hence the number P is divisible by the least common multiple of 3 and 7

That is LCM of 3 and 7

Since 3 and 7 are coprime, the LCM of 3 and 7 is 21

Hence the number P is divisible by 21

Hence if a number is divisible by both 3 and 7, then the number is also divisible by 21

∴ The correct answer is 21

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