Question

hcf and lcm of 20 and 30

Answer 1

Prime factorisation of 20 = $2\times 2\times 5$
And prime factorisation of 30 = $2\times 3\times 5$
So H.C.F of 20 and 30 = $2\times 5=10$
And L.C.M of 20 and 30 is given by;
$$\begin{gathered} 2\left|20,30\right| \\ \overline{5\left|10,15\right|} \\ \overline{\left|2,3\right|} \end{gathered}$$
Therefore L.C.M of 20 and 30 = $2\times 5\times 2\times 3=60$