Scientific notation is always in the form:
#color(white)("XXX")color(red)("mantissa with one digit to the left of the decimal point")xx10^color(blue)("scaling exponent")#
So
#color(white)("XXX")339# must be written with a #color(red)("mantissa")# of #color(red)(3.39)#
The #color(blue)("scaling exponent")# is the number of times the #color(red)("mantissa")# must be multiplied by #10# to get the intended value.
#color(white)("XXX")3.39xx10^0=3.39color(white)("XXX")#not intended value.
#color(white)("XXX")3.39xx10^1=33.9color(white)("XXX)#not intended value
#color(white)("XXX")3.39xx10^2=339color(white)("XXXx")color(green)("intended value")#