In the series 9 N ! 3 P Q 6 E 1 V # 8 L 2 Z 7 A, what is the sum of the digits that stand at the odd-numbered places of the series — the first place, the third place, the fifth place and so on?

The odd-numbered places hold 9, !, P, 6, 1, #, L, Z and A. Of these only 9 (place 1), 6 (place 7) and 1 (place 9) are digits, and 9 + 6 + 1 = 16. Answering 20 is the sum of the digits at the even-numbered places (3 + 8 + 2 + 7); 36 is the sum of every digit in the series, got by ignoring the restriction altogether; 17 comes of slipping one of the three addends.