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1. The average of the two-digit numbers, which remain the same when the digits interchange their positions , is :
- A. 33
- B. 33
- C. 33
- D. 33
Answer: Option C
Explanation:
= 11 + 22 + 33 + 44 + 55 + 66 + 77 + 88 + 999 = (11 + 99) + (22 + 88) + (33 + 77) + (44 + 66) + 559 = 4 × 110 + 559 = 4959 = 55.
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