Question in image! Thanks for help! (Also im posting more questions like this so if these are easy for you keep a eye out on my profile for a little bit!)

Describe all the numbers that when rounded to the nearest thousand are 645,000

Adriana sold 50 shares of a company’s stock through a broker. the price per share on that day was $22.98. the broker charged her a 0.75% commission. what was adriana’s real return after deducting the broker’s commission? a. $8.62 b. $229.80 c. $1,140.38 d. $1,149.00

What is the simplified form of (3.25x10^3)(7.8x10^6) written in scientific notation?