+539 From 5! and beyond, the units digit is always 0 since there is always a multiple of five in there. SO we only have to focus on 1! and 3!. 1! is 1, and 3!=3*2=6. 6+1=7.
7 is the units digit.
+539 From 5! and beyond, the units digit is always 0 since there is always a multiple of five in there. SO we only have to focus on 1! and 3!. 1! is 1, and 3!=3*2=6. 6+1=7.
7 is the units digit.
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