(1)46.5×99+46.5, =46.5×(99+1), =46.5×100, =4650; (2)4.85×1.25×8, =4.85×(1.25×8), =4.85×10, =48.5; (3)(455-12.5×4)÷8.1, =(455-50)÷8.1, =405÷8.1, =50; (4)39÷0.125÷0.8, =39÷(0.125×0.8), =39÷0.1, =390.