Art of Problem Solving

2021 AIME I Problems/Problem 3: Difference between revisions

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==Solution==
==Solution==
<math>\binom{11}{2} = 55</math> We need to subtract 5 since <math>2^10 - 2^0, 2^1, 2^2, 2^3, 2^4</math> don't work. <math>55-5=\boxed{050}</math> ~hansenhe
<math>\binom{11}{2} = 55</math> We need to subtract 5 since <math>2^{10} - 2^0, 2^1, 2^2, 2^3, 2^4</math> don't work. <math>55-5=\boxed{050}</math> ~hansenhe


==See also==
==See also==

Revision as of 18:22, 11 March 2021

Problem

Find the number of positive integers less than $1000$ that can be expressed as the difference of two integral powers of $2.$

Solution

$\binom{11}{2} = 55$ We need to subtract 5 since $2^{10} - 2^0, 2^1, 2^2, 2^3, 2^4$ don't work. $55-5=\boxed{050}$ ~hansenhe

See also

2021 AIME I (ProblemsAnswer KeyResources)
Preceded by
Problem 2
Followed by
Problem 4
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
All AIME Problems and Solutions

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