Q84 / 180 · KCET 2011 · Mathematics

The digit in the unit's place of $7^{171}+(177) !$ is

  • A
    3
  • B
    2
  • Correct answer
    C
    1
  • D
    0

Solution

Given expression $$ (7)^{171}+(177) ! $$ We know that the cycle of 7 is 4 , i.e., $(7)^{3}=1$ and in case of more the 4 number in factorial notation gives always 0 at unit place. $$ \Rightarrow \quad\left(7^{3}\right)^{57}+(177) !=1+0=1 $$

Hence, the correct answer is option: 'C'.

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