Previous Year Paper
CAT2003Previous Years Paper
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 code are there for which no such confusion can arise?
A  80 
B  78 
C  71 
D  69

The total codes which can be formed = 9 × 9 = 81. (Distinct digit codes)
The digits which can be confusing are 1, 6, 8 and 9 from these digit we can form the codes = 4 × 3 = 12
Out of these 12 codes two numbers 69 and 96 will not create confusion
Therefore, (12 − 2) = 10 codes will create a confusion.
Therefore the total codes without confusion = 81 – 10 = 71.
CAT2003Previous Years Paper Flashcard List
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