you just multiply 1.5x10^3 by 4.3x10^2. 1.5x10^3 is equal to 1500 (move the decimal to the right as many spaces as the exponent gives) and 4.3x10^2 is equal to 430. 1500*430=645000. To get that back down to scientific notation, we would have to move the decimal back to between the 6 and 4 to get 6.45 (Zeros aren't included in scientific notation) We moved the decimal to the left five spaces do the exponent is 10^5. We are left with 6.45x10^5
