When a number between 0 and 1 is written using scientific notation, the exponent will be negative. When a number greater than 1 is written using scientific notation, the exponent will be positive.
This is because scientific notation consists of a number multiplied by 10 to some degree. If this degree is negative, it is like you were dividing by multiples of 10, or moving the decimal place to the the left, which makes the number smaller. If the degree is positive, you are multiplying by multiples of 10, which would be moving the decimal place to the right and making the number larger.
