- p, q, r and s are one of the digits 1, 7, 5 or 6, with each digit used only once. How many different values of p × s + r × q can be obtained?
- A television channel has eight shows – A,B, K,L,M,N,Y,Z − which are available for three prime-time slots on a Wednesday evening. In how many different ways can the shows be shown, if show A can come only after program B provided that maximum of 1 show can run in 1 slot ?
- Ravi has a board, similar to a chessboard, except that it has only 6 × 6 squares. He calculated the number of rectangles (including rectangle whose length and breadth are equal) on the board. How many distinct values can the area of these rectangles assume?

# p, q, r and s are one of the digits 1, 7, 5 or 6, with each digit used only …

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