Find HCF of $14, 42$ and $84$.

LCM and HCF

1. If the numbers $n_1$ and $n_2$ are exactly divisible by the same number $x$, then $x$ is a common divisor of n1 and n2. The highest of all the common divisors of $n_1$ and $n_2$ is called as the GCD or the HCF.

2. Co-prime numbers are any two numbers which have an HCF of $1$. (Two consecutive natural numbers are always co-prime. Two consecutive odd numbers are always co-prime. Two prime numbers are always co-prime.)

3. HCF of two or more fractions is given by: $\frac{HCF of numerators}{LCM of denominators}$

4. LCM of two or more fractions is given by: $\frac{LCM of numerators}{HCF of denominators}$

5. LCM $\times$ HCF $=$ Product of two numbers $\left(n_1\times n_2\right)$