To turn a number into scientific notation, move the decimal point so that there is only 1 number to the left of the decimal point.
Count the number of spaces you moved the decimal point.
If you move the decimal point to the right, the exponent is negative, if you move it to the left the exponent is positive.
0.000075
You need to move the decimal point 5 places to the right to get 7.5
Because it was moved to the right, the exponent is negative 5
The answer would be 7.5 x 10^-5 which is B.
