Question

Find all the natural numbers which are less than 24 and also coprime to it.

Answer 1

Two numbers are said to be co-prime if they have no common factors except 1.
Factors of 24 = 1, 2, 3, 4, 6, 8, 12 and 24.
Now, to find the number which are less than 24 and also coprime to it.
We have to look for all the prime number which are less than 24 and the numbers are 2, 3, 5, 7 , 11, 13, 19 and 23.
Factors of 2: 1, 2
Factors of 3: 1, 3
Factors of 5: 1, 5
Factors of 7: 1, 7
Factors of 11: 1, 11
Factors of 13: 1, 13
Factors of 19: 1, 19
Factors of 23: 1, 23
Now, among these numbers we can take 5, 7, 11, 13, 19 and 23.
Hence, there are 6 numbers which are less than 24 and also co-prime to it.