The problem presented is to find the missing number in the equation:

$5,809,621 = 5,000,000 + \_\_\_\_ + 8,000 + 600 + 20 + 1$

We need to identify the missing component that, when added, will complete the given number.

Breaking it down:

• $5,000,000$ accounts for the millions place.
• The missing number will account for the hundred thousands place.
• $8,000$ accounts for the thousands place.
• $600$ accounts for the hundreds place.
• $20$ accounts for the tens place.
• $1$ accounts for the units place.

Given the number $5,809,621$, the digit in the hundred thousands place is $800,000$.

So, the missing number in the blank should be $800,000$.

Thus, the correct answer is option (4) $800,000$.

Would you like further details or have any questions?

Here are some related questions:

1. What is the value of each digit in the number 5,809,621?
2. How can you write 5,809,621 in expanded form?
3. How do you determine the place value of a digit in a number?
4. What is the sum of the digits in the number 5,809,621?
5. Can the number 5,809,621 be broken down into smaller numbers using place value?

Tip: Always break down large numbers into their place values to better understand and solve similar problems.