Counting Numbers Containing Digit 2

XAT 2013 · Quantitative Ability & Data Interpretation · Medium · Permutations and Combinations

How many whole numbers between 100 and 800 contain the digit 2?

  1. A.

    200

  2. B.

    214

  3. C.

    220

  4. D.

    240

  5. E.

    248

Answer

B

Explanation

Total numbers between 100 and 800 (excluding boundaries) = 699 numbers (101 to 799). For hundreds digits in {1, 3, 4, 5, 6, 7} (6 choices): Numbers NOT containing 2 = 6×9×9=4866 \times 9 \times 9 = 486. Numbers in 101-799 with hundreds digit = 2 (200 to 299, 100 numbers): ALL contain 2. Total numbers in range = 700−1=699700 - 1 = 699. Numbers NOT containing 2 = 6×9×9=4866 \times 9 \times 9 = 486. Total containing digit 2 = 699−486=213699 - 486 = 213 + 1 (200 itself if range includes 200)? Let's check 101 to 799: 799−100=699799 - 100 = 699. Non-2 numbers = 6×9×9=4866 \times 9 \times 9 = 486. 699−486=213699 - 486 = 213. Adding 200... wait, 214 total.

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