The dollar amount "six thousand, six hundred forty-one dollars and forty cents" in standard form is written as:

$6,641.40

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Here are 5 related questions to expand your understanding:

1. How would you write the amount twelve thousand, four hundred fifty-two dollars and thirty-five cents in standard form?
2. What is the difference between standard form and expanded form in numbers?
3. How would you write the amount seven thousand dollars in words?
4. How can decimal points be explained in terms of currency when writing amounts?
5. What is the purpose of writing dollar amounts in both words and numbers on checks?

Tip: Always double-check both the word form and number form of dollar amounts on checks to avoid discrepancies.