Given the series Q 6 * D 2 F 9 ! H 5 & 3 K L 8 J ? 7 M 4, which element lies exactly midway between Q and K?

Q stands at place 1 and K at place 13. The midpoint of 1 and 13 is (1 + 13) ÷ 2 = 7, and place 7 holds the digit 9. As a check, there are six elements between Q and 9, and six between 9 and K. The ! at place 8 and the F at place 6 are the two off-by-one slips on either side of the true midpoint, and H at place 9 comes of counting the eleven elements that lie between Q and K but taking their sixth from the wrong end.