Answer: 1.48971 x 10^19
Step-by-step explanation: 1-light year is approximately 5.865 x 10^12 which is 5,865,000,000,000 kilometers or 6 trillion miles in 1-year. The Andromeda galaxy is indeed 2.54 million light-years from Earth which is the closest galaxy to our Milky Way Galaxy.
The best way to this is to put this into a scientific calculator. If it shows 1.48971E19, the E stands for exponent and the 19 next to the E stands to the 19th power. That is written as 1,489,710,000,000,000,000 miles!! from Earth. That's a lot of zeros. That's the reason scientific notation is used; to avoid all those zeros and express very small/large figures.
Hope this explanation helps.