5×25×125×64,=5×25×125×(2×4×8),=(5×2)×(25×4)×(125×8),=10×100×1000,=1000000.故选:C.
125x5x8x6=125x8x5x6=1000x30=30000
125乘8乘5乘6=1000乘30=30000