So in scientific notation you have to have one non decimal followed by the rest of the number as a decimal, multiplied by a 10^( a number) that makes the number into that form. To find this number count the amount of steps the decimal point has to move to create this scenario. (in this case past the 3) So in this case the decimal moves 4 to the right so the number is -4 while if it was to the left it would be positive, so the answer is C
