1. The problem is to find the sum of the numbers: 2,400,000; 2,100,000; 1,800,000; 1,500,000; 1,200,000; and 900,000. 2. To find the sum, we add all the numbers together using the formula for sum of terms: $$\text{Sum} = a_1 + a_2 + a_3 + \cdots + a_n$$ 3. Adding the numbers step-by-step: $$2,400,000 + 2,100,000 = 4,500,000$$ $$4,500,000 + 1,800,000 = 6,300,000$$ $$6,300,000 + 1,500,000 = 7,800,000$$ $$7,800,000 + 1,200,000 = 9,000,000$$ $$9,000,000 + 900,000 = 9,900,000$$ 4. Therefore, the sum of the given numbers is: $$\boxed{9,900,000}$$