1. **State the problem:** Multiply 10000000000 by 2009000. 2. **Formula used:** Multiplication of two numbers $a \times b$. 3. **Intermediate work:** - Write numbers in scientific notation for easier multiplication: $$10000000000 = 10^{10}$$ $$2009000 = 2.009 \times 10^{6}$$ - Multiply the coefficients and add the exponents: $$10^{10} \times 2.009 \times 10^{6} = 2.009 \times 10^{(10+6)} = 2.009 \times 10^{16}$$ 4. **Final answer:** $$10000000000 \times 2009000 = 20090000000000000$$