Find the remainder when \(3 \times 13 \times 23 \times 33 \times \ldots \times 183 \times 193\) is divided by 5.
(3×13×23×33×43×...×183×193) mod 5 =1
[∏(3+10n), n=0 to 19] mod 5 =1 Remainder. From Wolfram/Alpha:
http://www.wolframalpha.com/input/?i=%5B%E2%88%8F(3%2B10n),+n%3D0+to+19%5D+mod+5+%3D%3F
+249 
