How do you calculate the square feet of a 10 foot garden circle that needs 2 inches mulch in it?

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Question by leeflea: How do you calculate the square feet of a 10 foot garden circle that needs 2 inches mulch in it?
I’m starting to make beds for spring planting and cannot remember how to calculate the square foot of a circle esp. when I have to take into consideration the two inches of mulch needed.
thank you,

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