PositionSmallest
PositionSmallest[list] gives the positions of the numerically smallest value in list.
PositionSmallest[list, n] gives the positions of the first n smallest values.
PositionSmallest[list, n, orderfun] gives the positions of the n smallest values as determined by orderfun.
Examples
Find position of the smallest element:
PositionSmallest[{5, 2, 8, 1, 9}]
(* {{4}} *)Find positions of the 3 smallest:
PositionSmallest[{5, 2, 8, 1, 9}, 3]
(* {{4}, {2}, {1}} *)Please visit the official Wolfram Language Reference for more details.