Buick

Uhm, if you want it correct then do these step, (6.91 x 10-2 power) + (2.4 x 10-3 power)= 0.691+2.4 = 3.091 x 10-3 power we move . from 6. to 0.6 because the power isn't the same so we add the lower power by moving dots and +1 the power or -1 if Neg^.