Number of 4-digit numbers that are less than or equal to 2800 and either divisible by 3 or by 11 , is equal to ____________.
Answer (integer)
710
Solution
Numbers which are divisible by 3 (4 digit) and less than or equal to 2800
<br/><br/>$=\frac{2799-1002}{3}+1=600$
<br/><br/>Numbers which are divisible by 11 (4 digit) and less than or equal to 2800
<br/><br/>$=\frac{2794-1001}{11}+1=164$
<br/><br/>Numbers which are divisible by 33 (4 digit) and less than or equal to 2800
<br/><br/>$=\frac{2772-1023}{33}+1=54$
<br/><br/>$\therefore$ Total numbers = $600+164-54=710$
About this question
Subject: Mathematics · Chapter: Permutations and Combinations · Topic: Fundamental Counting Principle
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