A bacteria culture grows to 1.2 x 10^6 cells in one hour and 2.5 x 10^6 cells in the next hour. How many cells are there in total after two hours in scientific notation?

A comet is traveling at a speed of 2.3 x 10^4 km/h. If it travels for 5 hours, how far does it go in scientific notation?

A researcher finds that a certain chemical is present in 6.7 x 10^3 mg in one sample and 2.1 x 10^3 mg in another. How much chemical is present in total in scientific notation?

An astronomer observes a star that is 3.0 x 10^20 km away. If another star is 1.5 x 10^20 km closer, how far is the second star from Earth in scientific notation?

A computer processes 1.5 x 10^9 calculations per second. If it runs for 2 seconds, how many calculations does it perform in total in scientific notation?

A factory produces 4.5 x 10^5 widgets in one day and 3.2 x 10^5 widgets the next day. How many widgets are produced over the two days in scientific notation?

A satellite orbits Earth at an altitude of 3.6 x 10^7 meters. If it descends by 1.2 x 10^7 meters, what is its new altitude in scientific notation?

A library has 2.5 x 10^4 books and receives a donation of 1.3 x 10^4 books. How many books does the library have now in scientific notation?

A car travels 1.8 x 10^3 km in the first leg of a journey and 2.4 x 10^3 km in the second leg. What is the total distance traveled in scientific notation?