The H.C.F of given monomials is the common factor having greatest coefficient and highest powers of the variables.

Ex: 1) Find H.C.F of 6x3y6x^{3}y and 18x2y318x^{2}y^{3}.

Sol: 6x3y=2×3×x3×y6x^{3}y = 2 \times 3 \times x^{3} \times y

 18x2y3=2×32×x2×y3\quad \quad \ 18x^{2}y^{3} = 2 \times 3^{2} \times x^{2} \times y^{3}

 H.C.F=2×3×x2×y\quad \quad \ \text{H.C.F} = 2 \times 3 \times x^{2} \times y

 =6x2y\quad \quad \quad \quad \quad \quad \ = 6x^{2}y

Ex: 2) Find H.C.F of 5xy5xy and 10x10x.

Sol: 5xy=5×x×y5xy = 5 \times x \times y

 10x=2×5×x\quad \quad \ 10x = 2 \times 5 \times x

 H.C.F=5x\quad \quad \ \text{H.C.F} = 5x

Ex: 3) H.C.F of 12a2b12a^{2}b and 15ab215ab^{2} is 3ab

Ex: 4) H.C.F of 2x2x and 44 is 2

Ex: 5) H.C.F of 12x12x and 3636 is 12

Ex: 6) H.C.F of 14pq14pq and 35pqr35pqr is 7pq