\(a,\left(-4\right).125.\left(-25\right).\left(-6\right).\left(-8\right)\)
\(=\left[\left(-4\right).\left(-25\right)\right].\left[125.\left(-8\right)\right].\left(-6\right)\)
\(=100.\left(-1000\right).\left(-6\right)\)
\(=-100000.\left(-6\right)\)
\(=600000\)