On the occasion of Deepawali festival each student of a class sends greeting cards to the others. If there are 20 students in the class, then the total number of greeting cards exchanged by the students is

On the occasion of Deepawali festival each student of a class sends gr

1.	On the occasion of Deepawali festival each student of a class sends greeting cards to the others. If there are 20 students in the class, then the total number of greeting cards exchanged by the students is
A.	\[^{20}{{C}_{2}}\]
B.	\[2\ .{{\ }^{20}}{{C}_{2}}\]
C.	\[2\ .{{\ }^{20}}{{P}_{2}}\]
D.	None of these
Answer» C. \[2\ .{{\ }^{20}}{{P}_{2}}\]

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On the occasion of Deepawali festival each student of a class sends greeting cards to the others. If there are 20 students in the class, then the total number of greeting cards exchanged by the students is

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