Difference between revisions of "1995 AJHSME Problems/Problem 23"
Mrdavid445 (talk | contribs) (Created page with "==Problem== How many four-digit whole numbers are there such that the leftmost digit is odd, the second digit is even, and all four digits are different? <math>\text{(A)}\ 1120...") |
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<math>\text{(A)}\ 1120 \qquad \text{(B)}\ 1400 \qquad \text{(C)}\ 1800 \qquad \text{(D)}\ 2025 \qquad \text{(E)}\ 2500</math> | <math>\text{(A)}\ 1120 \qquad \text{(B)}\ 1400 \qquad \text{(C)}\ 1800 \qquad \text{(D)}\ 2025 \qquad \text{(E)}\ 2500</math> | ||
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| + | ==Solution== | ||
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| + | Count from left to right: There are 5 choices for the first digit, 5 choices for the second, 8 remaining choices for the third, and 7 remaining for the fourth, so there are <math>5*5*8*7=1400 \text{(B)}</math> numbers. | ||
Revision as of 14:34, 5 July 2012
Problem
How many four-digit whole numbers are there such that the leftmost digit is odd, the second digit is even, and all four digits are different?
Solution
Count from left to right: There are 5 choices for the first digit, 5 choices for the second, 8 remaining choices for the third, and 7 remaining for the fourth, so there are 
numbers.
