Move the decimal so there is one non-zero digit to the left of the decimal point. The number of decimal places you move will be the exponent on the 10. If the decimal is being moved to the right, the exponent will be negative. if the decimal is being moved to the left, the exponent will be positive. all i really did was subtract the numbers without the exponents. but this is useless right now so the answer is: 2.1*10^7
Basically: 2.1 times 10 to the power of 7