| Find the remainder when \[{{7}^{1987}}\] is divided by 5. [NICL (AAO) 2011] |
A) 1
B) 2
C) 3
D) 4
E) None of these
Correct Answer: C
Solution :
| \[{{7}^{1987}}={{7}^{4\,\times \,446}}\cdot {{7}^{3}}\] |
| \[={{1.7}^{3}}\] \[[\because {{7}^{4}}=1\,\,unit\,digit]\] |
| \[=343\] |
| 343 divided by 5, then remainder is 3. |
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