When working with scientific notation, a useful rule of thumb is:

If the decimal point moves to the LEFT:

#rarr# the power of #10# INCREASES by #1# for each place moved.

#" "4color(blue)(50,000,000.) xx 10^0 = 4.5 xx 10^color(blue)(8)#

#" ".larrlarrlarr." "#(the decimal point moved #8# places left)

If the decimal point moves to the RIGHT:

#rarr# the power of #10# DECREASES by #1# for each place moved.

#" "0color(red)(.000,784) xx 10^0 = 7.84 xx 10^color(red)(-4)#

#" ".rarr." "#(the decimal point moved #4# places right)

Sometimes in calculations, numbers are obtained which are not in scientific notation. These have to be adjusted so that there is only ONE digit before the point.

#17.3 xx 10^15 = 1.73 xx 10^16#

#156 xx 10^-9 =1.56 xx 10^-7#

#0.00423 xx 10^18 = 4.23 xx 10^15#

#0.000,008,91 xx 10^-5 = 8.91 xx 10^-11#