Question
Question: Digit at unit place of sum (1!)<sup>2</sup> + (2!)<sup>2</sup> + (3!)<sup>2</sup> ……… + (2008!)<sup...
Digit at unit place of sum
(1!)2 + (2!)2 + (3!)2 ……… + (2008!)2 is
A
5
B
7
C
9
D
None
Answer
7
Explanation
Solution
Q S = 1 + 4 + 36 + 576 + …….. + (2008!)2
= 617 + all other terms will have 0 at unit place