According to WolframAlpha: https://www.wolframalpha.com/input/?i=17%5E1993
The tens digit is 9
What is the tens digit of 171993?
171993(mod100)≡(172)996+1(mod100)≡(172)996∗17(mod100)172=289≡89≡89−100≡−11(mod100)≡(−11)996∗17(mod100)≡((−11)2)498∗17(mod100)≡(121)498∗17(mod100)|121≡21(mod100)≡(21)498∗17(mod100)≡(21)5∗99+3∗17(mod100)≡(215)99∗213∗17(mod100)|215≡01(mod100)≡(1)99∗213∗17(mod100)≡213∗17(mod100)≡157437(mod100)≡37(mod100)
The tens digit is 3