document.write( "Question 933287: how many odd numbers are there greater than 1000 and less then 100000 \n" ); document.write( "

Algebra.Com's Answer #567213 by Edwin McCravy(20060) $\"\"$ $\"About$

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how many odd numbers are there greater than 1000 and less then 100000.
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document.write( "There are three methods to do this.  Take your pick.\r\n" );
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document.write( "Method 1:\r\n" );
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document.write( "First find the number of counting numbers greater than 1000 and lestt than 100000.\r\n" );
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document.write( "There are 99999 counting numbers from 1 to 99999, inclusive and we must subtract\r\n" );
document.write( "the first 1000, leaving 99999-1000 = 98999.  Half that is 49499.5. Since the\r\n" );
document.write( "first number is 1 and the last number is 99999, and they are both odd, then\r\n" );
document.write( "there are 49499 even ones and 49500 odd ones.\r\n" );
document.write( "Answer: 49500.\r\n" );
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document.write( "Method 2;\r\n" );
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document.write( "4 digit numbers:\r\n" );
document.write( "Choose the 1st digit 9 ways, {1,2,3,4,5,6,7,8,9}\r\n" );
document.write( "Choose the 2nd digit 10 ways, {0,1,2,3,4,5,6,7,8,9} \r\n" );
document.write( "Choose the 3rd digit 10 ways, {0,1,2,3,4,5,6,7,8,9}\r\n" );
document.write( "Choose the 4th digit 5 ways,  {1,3,5,7,9}\r\n" );
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document.write( "9x10x10x5 = 4500\r\n" );
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document.write( "5 digit numbers:\r\n" );
document.write( "Choose the 1st digit 9 ways, {1,2,3,4,5,6,7,8,9}\r\n" );
document.write( "Choose the 2nd digit 10 ways, {0,1,2,3,4,5,6,7,8,9} \r\n" );
document.write( "Choose the 3rd digit 10 ways, {0,1,2,3,4,5,6,7,8,9}\r\n" );
document.write( "Choose the 4th digit 10 ways, {0,1,2,3,4,5,6,7,8,9}\r\n" );
document.write( "Choose the 1st digit 5 ways,  {1,3,5,7,9}\r\n" );
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document.write( "9x10x10x10x5 = 45000\r\n" );
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document.write( "Total:  4500+45000 = 49500\r\n" );
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document.write( "Method 3:\r\n" );
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document.write( "The odd numbers from 1001 through 49999 form an arithmetic\r\n" );
document.write( "sequence with , , and d=2.  So we use\r\n" );
document.write( "the formula:\r\n" );
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document.write( "Edwin

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