When you convert a number to scientific notation, you have to move the decimal right or left so that the whole number falls between 1 and 10. You then "describe" what you would multiply by to get the original number by multiplying by 10^x. x is the number of decimal places you moved. If you move the decimal to the left, it will be a positive exponent. If you move the decimal to the right it will be a negative exponent. Here are some examples...
