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Forum URL: http://www.cut-the-knot.org/cgi-bin/dcforum/forumctk.cgi
Forum Name: Middle school
Topic ID: 38
#0, Converting Base Numbers
Posted by Shirley Reeves (Guest) on Mar-10-01 at 11:08 PM
I have a math problem for a college class that I have no idea how to do.
Given the base two number 10110100 base2, give the brief explanation of how this number could be converted directly to a base eight numeral (without firsst converting to base 10 and then back to base 8)
(HINT: 10 110 100 base 2= 264 base 8 )

#1, RE: Converting Base Numbers
Posted by alexb on Aug-03-01 at 03:17 PM
In response to message #0
LAST EDITED ON Aug-03-01 AT 03:21 PM (EST)


binary octal
000 0
001 1
010 2
011 3
100 4
101 5
110 6
111 7


Now,

(1101011)2 = (1 101 011)2 =

(011)2 + (101)2·23 + 1· 26 =

(3)8 + (5)8·81 + 1· 82 = (153)8


#2, RE: Converting Base Numbers
Posted by brian on Oct-08-01 at 09:39 AM
In response to message #0
You are converting to octal so each position is a power of 8 so 264 is 2X64+6+64+4 becasue of the numbering systems you can do this by counting off units of 3 from the right and converting to decimal and as the largest 3 digit binary number 111=7 this converts directly into octal.

so 001000 =10 in octal = 8 in decimal
001111 =17 in octal = 15 in decimal
010000 =20 in octal = 16 in decimal
etc
111000 =70 in octal = 48 in decimal