\(75^6-45^6\)
\(=\left(75^2\right)^3-\left(45^2\right)^3\\ =\left(75^2-45^2\right)\left(75^4+75^2.45^2+45^4\right)\\ =\left(75-45\right)\left(75+45\right)\left(75^4+75^2.45^2+45^4\right)\\ =30.120.\left(75^4+75^2.45^2+45^4\right)\\ =3600.\left(75^4+75^2.45^2+45^4\right)⋮3600\left(Dfcm\right)\)