Answer:
3.643×10^(-1)
Explanation:
Count the zeroes to the right of the decimal point before the leading 3: there are 0 zeroes.
If you count the leading digit 3, there is 1 digit to the right of the decimal point.
So: 0.3643 = 3.643×10^−1
Hope This Helps!
(BTW this is from Khan Academy)