1. The problem statement, all variables and given/known data An intelligence agency forms a code of two distinct digits selected from 0, 1 , 2…, 9, such that the first digit of the code is nonzero. The code, handwritten on a slip, can, however, potentially create confusion when read upside down - for example; the code 91 may appear as 16. How many codes are there for which no such confusion can arise? 2. The attempt at a solution This is the methodology I used: Since the first digit cannot be zero, therefore it can be chosen in 9 ways while no restriction occurs on the second number, therefore it can be chosen in 10 ways.Thus, the total number of ways is 10*9=90... Since 1,6,8,9 can create confusion, therefore there exist 12 such numbers which will create confusion. However the pair 69 and 96 do not come under this category.