Question

find the highest common factor of the given numbers by prime factorization​

Answer 1

Prime factorisation of the given numbers are :

54=2×3×3×3

72=2×2×2×3×3

90=2×3×3×5

Notice that 2 occurs as a common prime factor at least one times and 3 at least two times in given numbers.

∴ H.C.F =2×3×3=18