e is the exponent of the number, therefore it is the number which 10 is raised by, so -4.
Which means -1.7 will be multipled by 10 raised to the -4 power, so 1 is obviously correct.
Additionally, This is in scientific form. You can also write this in standard form in decimals, 10^-4 means it is 4 decimal places ahead the original number so you can move the decimal point back 4 places and add 0s, you will see that -0.00017 is also in fact correct.
