How many positive 4-digit integers begin (on the left) with an odd digit and end with an even digit?
Show Hint
- \( 250 \)
- \( 500 \)
- \( 2,000 \)
- \( 2,500 \)
- \( 5,000 \)
The Correct Option is D
Solution and Explanation
Step 2: First digit (odd): 1, 3, 5, 7, 9 (5 choices).
Step 3: Last digit (even): 0, 2, 4, 6, 8 (5 choices).
Step 4: Middle 2 digits: 0-9 (10 choices each), total = \( 5 \times 10 \times 10 \times 5 = 2,500 \).
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