What is the digit in the unit place of the number 1^1 \times 3^3 \times 5^5 \times 7^7 \times 9^9 ?

Explanation

The term 5^5 ends in 5. All other bases (1, 3, 7, 9) are odd, so their powers are odd. The product of an odd number and a number ending in 5 will always yield a number ending in 5.

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