whole number sense. Help needed

alice · 2009-02-28 23:09:51

I've been having a lot of trouble with this question, it would be great if someone helped me out.

N is a Six-digit number. the left-most digit is 1. if the 1 is removed then written as the right-most digit, the number obtained is three times N. find N

JaneFairfax · 2009-02-28 23:39:29

Last edited by JaneFairfax (2009-03-02 00:39:31)

alice · 2009-03-01 23:06:29

i didn't really understand your working out, could you please explain it?

JaneFairfax · 2009-03-02 00:48:14

janetpc2008 · 2009-03-02 04:57:00

This is how I would do it:
N is the number you are trying to find.
You are told it is a 6 digit number and the left most number is 1.
To remove the 1 is to say N-100000.
To add the 1 on the right is to multiply the thing by 10 and then add 1. This would be then: 10*(N-100000)+1

We are told that this new number 10*(N-100000)+1 must equal 3* the original number (which was N). So we have an equation:

10*(N-100000)+1=3*N
solving: 10*N - 10*100000 + 1 = 3*N
then: 10*N-3*N - 1000000 + 1 = 0
then: 7*N = 999999
finally: N=999999/7 = 142857

Math Is Fun Forum

#1 2009-02-28 23:09:51

whole number sense. Help needed

#2 2009-02-28 23:39:29

Re: whole number sense. Help needed

#3 2009-03-01 23:06:29

Re: whole number sense. Help needed

#4 2009-03-02 00:48:14

Re: whole number sense. Help needed

#5 2009-03-02 04:57:00

Re: whole number sense. Help needed

Board footer