Answer :

SlowZasob
20 000 is as much as 20 * 1 000, so we can write it as: 20 * 10^3
3 400 000 is as much as 34 * 100 000, so we can write it as: 34 * 10^5

The sum in scientific notation would look like this:

20 * 10^3 + 34 * 10^5

I hope that's what you meant :)
FirstSineOfMadness
Scientific notation means representing something as a number on (0,10) exclusive, with a power of ten.
Example: 47,573,018 would be 4.7573018 x10^7
Your numbers 20,000 and 3,400,000 can be represented as 2x10^4 and 3.4x10^6
You can bring these together by changing them so they have the same power of ten, rounding down.
=> 2x10^4 + 340x10^4 => 342x10^4 => 3.42x10^6
Final answer:
20,000+3,400,000=3.42x10^6
Hope I helped :)