1. State the problem: We need to find the sum of three numbers: $263350000$, $1100000000$, and $24909000$. 2. Add the first two numbers: $$263350000 + 1100000000 = 1363350000$$ 3. Add the result to the third number: $$1363350000 + 24909000 = 1388259000$$ 4. The sum of the three numbers is $$1388259000$$.