How can I add and subtract numbers written in scientific notation?
Best to write both numbers in standard notation if you can't use a calculator.
Let's add 4.723 x
Write the numbers so that columns are matched up appropriate which would place the 8 directly under the 2.
This allows us to find an answer of 4803000 or 4.803 x
If you need to worry about significant figures, you should report an answer of 4.80 x
You can use the same trick for really small numbers, just make sure you line up the decimal points from both numbers.