Register to reply 
Missing 3, 6 and 9'sby Hippasos
Tags: power of 3 6 and 9 
Share this thread: 
#1
Feb813, 03:35 PM

P: 72

1/56=0,017857142857142857142857...142857
1/7=0,142857142857142857142857...142857 142857 142857/7= 20408,142857142857142857...142857 20408/7= 2915,42857142857142857...142857 2915/7= 416,42857142857142857142857...142857 416/7= 59,42857142857142857142857...142857 59/7= 8,42857142857142857142857...142857 8/7 1,142857142857142857142857...142857 Missing decimal numbers 3  why are these"missing"? Not needed even during calculations  at all? Can You please explain? 


#2
Feb813, 03:38 PM

PF Gold
P: 6,492

what's to explain? it's just the result of particular calculations.
Hey, try 1/3 = .333333 you don't need 1,2,4,5,6,7,8, or 9 Explain that ! 


#3
Feb913, 01:58 AM

P: 72




#4
Feb1113, 12:38 PM

Emeritus
Sci Advisor
PF Gold
P: 7,334

Missing 3, 6 and 9's
Hey! don't dismiss your observation so quickly. It is very interesting and if you look at the long division process you can see just why there are no 3 or multiples of, in the decimal expansion.
First of all observe that there are at most 6 digits possible. There is a limited set of possible remainders in the long division process{1,2,3,4,5,6}. A zero would terminate the process, 7 and greater means that you have not made a correct choice of a multiplier. This implies that there can be at most 6 digits in the expansion. 7 is unique in that it is the only integer with the max possible number of unique digits in the decimal expansion. Now lets go through the long division process and see if we can see why 3 does not appear. The first step: 10/7 = 1 r 3 : so 1 is the first digit the remainder sets up the second step, r*10 30/7 = 4 t 2 : so 4 is the 2nd digit. 20/7= 2 r 6 : so 2 is the 3rd digit. now we can see why 3 does not appear, each of the steps involves a multiple of 10 divided by 7. But the only way to get a 3 would be if you could have a non zero as the last digit, this cannot happen. Since 7*3=21 and 7*4=28. I also find this an interesting little tidbit. Hope I helped throw some light on it for you. 


Register to reply 
Related Discussions  
Missing Matter  Is anything really Missing  Cosmology  15  
Missing Matter, Missing Energy?  Cosmology  8  
Am i missing something?  Calculus & Beyond Homework  1  
Am I missing something?  Introductory Physics Homework  1  
I'm missing something  help  Introductory Physics Homework  1 