As demonstrated a little bit of thought and algebra can go a long way. Find the number of subsets of the set 1 2 3 4 5 6 7 8 9 10 having 3 elements. Displaystyle r r objects from the set is.
The number of combinations of n things taken r at a time is written as C n r.
The formula for a combination is nCr n r. Formula for Combinations of n Distinct Objects. The number of combinations of n things taken r at a time is written as C n r. The word has followed by a space and a number.