①3.47×10的-4次方 =3.47×0.0001=0.000347
②-6×10的-7次方 =-6×0.0000001=-0.0000006
③-8.61×10的-2次方=-8.61×0.01=-0.0861
④9.401×10的-3次方=9.401×0.001=0.009401