document.write( "Question 249147: What is the remainder when 2 ^ 2006 is divided by 17 ? \n" ); document.write( "
| Algebra.Com's Answer #181514 by Theo(13342)     You can put this solution on YOUR website! Apparently there is no easy way to do this.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "I found the answer here.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the answer was not complete but it started me on my way to finding out how it was done.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "here's what I found.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you need to find a pattern.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if you follow the directions you will see that the pattern is every 8 exponents.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "2^0 = 1 / 17 = remainder of 1 \n" ); document.write( "2^8 = 256 / 17 = remainder of 1 \n" ); document.write( "2^16 = 65536 / 17 = remainder of 1\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the first 8 numbers in the sequence are:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "2^0 = 1 / 17 = 0 with a remainder of 1 \n" ); document.write( "2^1 = 2 / 17 = 0 with a remainder of 2 \n" ); document.write( "2^2 = 4 / 17 = 0 with a remainder of 4 \n" ); document.write( "2^3 = 8 / 17 = 0 with a remainder of 8 \n" ); document.write( "2^4 = 16 / 17 = 0 with a remainder of 16 \n" ); document.write( "2^5 = 32 / 17 = 1 with a remainder of 15 \n" ); document.write( "2^6 = 64 / 17 = 3 with a remainder of 13 \n" ); document.write( "2^7 = 128 / 17 = 7 with a remainder of 9 \n" ); document.write( "2^8 = 256 / 17 = 15 with a remainder of 1 and the pattern starts all over again.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "what happens if you are given 2^9 / 17 and are asked to find the remainder.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you can actually solve this, and your answer will be 2 because the pattern repeated all over again.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "2^9 = 512 / 17 = 30 with a remainder of 2.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if the number was very large, like 2^2006, you can't do this.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If you know the repeating pattern, however, you can figure it out.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "since the pattern repeats every 8 exponents, just divide 9 by 8 to get 1.something.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "take the integer part and multiply it by 8 to get 8.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "subtract 8 from 9 to get 1.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your 2^9 remainder is equivalent to the remainder of 2^1.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "That remainder equals 2.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "try it again with a larger number.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "suppose your number is 2^20 / 17 and they want to know what the remainder is.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "take the exponent of 20 and divide it by 8 to get 2.5\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "take the integer part of the answer and multiply it by 8 to get 2 * 8 = 16\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "subtract 16 from 20 to get 4.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your remainder will be equivalent to the remainder of 2^4 which would equal 16\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "again, this is small enough that we can prove it, so:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "2^20 = 1048576 / 17 = 61680.94118 and the remainder is .9411765 * 17 = 16\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "there will be some rounding errors, but 16 is the remainder and the equivalent of 2^4 remainder is also 16 so we're good.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "applied to your problem, you would do the following:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "2^2006 / 17 = remainder of ?????\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "take 2006 and divide it by 8 to get 250.75\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "multiply 8 by 250 to get 2000.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "subtract 2000 from 2006 to get 6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your remainder will be equivalent to the remainder of 2^6.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that would equal 13\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "I calculated up to 2^23 just to ensure myself that the pattern repeated every 8 exponents.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "It does, but you have to start from 2^0 in order to see that for the first 8 exponents.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "2^7 - 2^0 = 8\r \n" ); document.write( "\n" ); document.write( "2^7 equals a remainder of 9 \n" ); document.write( "2^(7+8) = 2^15 equals a remainder of 9 \n" ); document.write( "2^(15+8) = 2^23 equals a remainder of 9\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Once the number of exponents in the repeating pattern was derived, the rest was how to apply that number to the exponents which is the procedure I just gave you.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |