d no of  different signals can b made by 5 flags from 8 flags of different colours  is

d no of all possible nos formed  out of 1,2,3,4 widout repition is

ans dis

Regarding the first, I think different colours will give different signals.

So, to give a unique signal,you'll put 5 different colours together

It should be permutations..

Because V-I-B-G-Y is a different signal and V-I-B-Y-G is different

So the answer should be ⁸P₅...that comes to 6720.

About the second, see you have four digits.

no repititions allowed..but there's no bar on number of digits..

So you can have numbers of one digit..which are ⁴P₁..

Similarly for two,you have ⁴P₂..

and so on,

so finally,you sum these four..you'll get 54 (as correctly shown by Decoder)