Not always between 1 and 10...
The general convention is to adjust the power of 10 so that the prefactor in scientific notation has a value between 1 and 10.
Situations arise, however, where it is useful to express the number using a unconventional power of 10. Note that the following are all equivalent:
375,000 = 3.75 x 105 = 37.5 x 104 = 375. x 103 = …= (all are correct; only the colored one is conventional)
0.000469 = 4.69 x 10-4 = 0.469 x 10-3 = 469. x 10-6 =…=
(all are correct; only the colored one is conventional)