Formula, method and derivation to find the number of ways in which a positive integer can be expressed as a product of two co prime factors. Factors that are relatively prime to each – i.e., two factors whose HCF is 1.

The Method

Step 1: Prime factorize the given number.

Step 2: Count the number of prime factors. Let us say the number has ‘x’ prime factors. Note, count only the prime factors.

For example, if the number is 28, it can be prime factorized as 2^2 * 7. 28 has 2 prime factors viz., 2 and 7.

Step 3: Number of ways of expressing the number as product of 2 co prime factors = 2^(x – 1), where x is the number of prime factors of the number.

The video not just gives you this formula but also derives the formula provides the logic behind why the method works.

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