CUET Preparation Today
What is the last digit of $17^{17}$ ? |
3 1 5 4 |
1 |
The correct answer is option (2): 1 $17^{17}(mod\, 10)$ $17≡7(mod\, 10)$ $17^2 ≡ 7^2 (mod\, 10)$ $17^2 ≡49 (mod\, 10)$ $17^2≡9(mod\, 10)$ $(17^2)^2≡9^2(mod\, 10)$ $17^4 ≡81(mod\, 10)$ $17^4 ≡1(mod\, 10)$ $17^4)^4≡1^4(mod\, 10)$ $17^{16}≡1(mod\, 10)$ $17^{16}= 1$ |
