Ask your own question, for FREE!
Mathematics 21 Online
OpenStudy (anonymous):

Hey I was just wondering...

OpenStudy (anonymous):

I was trying to count in base 2 like 1, 2, 10, 11.....and so on. Can u all help if u know it

jimthompson5910 (jim_thompson5910):

it goes: 0, 1, 10, 11, 100, 101, 111, etc the digit "2" does not exist in base 2

jimthompson5910 (jim_thompson5910):

this is analogous to saying that the digit "10" doesn't exist in base 10 the digits "1" and "0" do, but not "10"

jimthompson5910 (jim_thompson5910):

base 2 is also known as the binary counting system which is used extensively in computing (since 0 represents "off" and 1 represents "on" in a circuit)

OpenStudy (anonymous):

oh okay, so then it is 111, 1001, 10000, 10001 etc correct?

OpenStudy (anonymous):

oh okay that's interesting too

jimthompson5910 (jim_thompson5910):

111, 1000, 1001, 1010, 1011, 1100, 1101, 1111, and so on here's a much longer list http://www.minus40.info/sky/binary.html

jimthompson5910 (jim_thompson5910):

the basic idea is that 1+1 = 10 in base 2

jimthompson5910 (jim_thompson5910):

and you use this idea to generate the next number (just add 1 to the previous number to get the next). Don't forget to carry

OpenStudy (anonymous):

hmm..yeah that makes sense and how would u count in base 7? does 6 not exist like... 0,1,2,3,4,5,6,10,11,12,13,14,15,16,100

jimthompson5910 (jim_thompson5910):

6 is the largest digit in base 7 7 is the largest digit in base 8 and so on (you go as high as the base, exclude the base itself)

jimthompson5910 (jim_thompson5910):

you have the right count though for base 7 0,1,2,3,4,5,6,10,11,12,13,14,15,16,100, ...

OpenStudy (anonymous):

okay and one more thing, if u want to explain..... how do we take 15 (in base 10) and turn it in base 7 number

OpenStudy (anonymous):

I have some clue but not a whole lot

jimthompson5910 (jim_thompson5910):

First divide 15 by 7 15/7 = 2 remainder 1 then you take that quotient (2) and divide it by 7 2/7 = 0 remainder 2 notice how the denominator is always the base (7)

jimthompson5910 (jim_thompson5910):

so in summary, we have 15/7 = 2 remainder 1 2/7 = 0 remainder 2 read the remainders in reverse. So read starting at the bottom and read up: 21 Therefore, 15 in base 10 = 21 in base 7 You'll often see it in this notation \[\Large 15_{10} = 21_{7}\]

jimthompson5910 (jim_thompson5910):

oh and you stop when you get a quotient of 0

jimthompson5910 (jim_thompson5910):

something to check your work with http://korn19.ch/coding/base_converter.php just don't rely on it completely (use it as a check, not something to do all your hw)

OpenStudy (anonymous):

so then 30 in base 7 would be... 42 ?

jimthompson5910 (jim_thompson5910):

going from base 7 to base 10 uses a different method

OpenStudy (anonymous):

this is not my homework :) jst curious thanks for the links tho

jimthompson5910 (jim_thompson5910):

oh you want to go from 30 base 10 to a number in base 7?

OpenStudy (anonymous):

no no 30 is in base 10

OpenStudy (anonymous):

yeah

jimthompson5910 (jim_thompson5910):

ok, then yes \[\Large 30_{10} = 42_{7}\]

OpenStudy (anonymous):

and 28 (in base 10) would be 4 in base 7 ?

jimthompson5910 (jim_thompson5910):

no

jimthompson5910 (jim_thompson5910):

28/7 = 4 remainder 0 4/7 = 0 remainder 4 read remainders in reverse to get 40 \[\Large 28_{10} = 40_{7}\]

jimthompson5910 (jim_thompson5910):

4 in base 7 = 4 in base 10 since 4 is less than 7

jimthompson5910 (jim_thompson5910):

again that calculator will confirm

OpenStudy (anonymous):

okay so how do u do the opposite? convert base 7 numbers to base 1o nos. ?

jimthompson5910 (jim_thompson5910):

give me an example to work with, which number do you want to use?

OpenStudy (anonymous):

34

jimthompson5910 (jim_thompson5910):

Let's focus on the base 10 number system

jimthompson5910 (jim_thompson5910):

34 in base 10 means 30 + 4 or 3*10 + 4*1

jimthompson5910 (jim_thompson5910):

notice how the 10 pops up

jimthompson5910 (jim_thompson5910):

and how 1 = 10^0

jimthompson5910 (jim_thompson5910):

so 34 = 3*10^1 + 4*10^0

jimthompson5910 (jim_thompson5910):

this breakdown is handy to convert from base 7 to base 10

jimthompson5910 (jim_thompson5910):

so now let's say we have 34 in base 7 34 base 7 = 3*7^1 + 4*7^0 34 base 7 = 3*7 + 4*1 34 base 7 = 21 + 4 34 base 7 = 25 base 10

jimthompson5910 (jim_thompson5910):

another example convert 345 in base 7 to base 10 345 base 7 = 3*7^2 + 4*7^1 + 5*7^0 345 base 7 = 3*49 + 4*7 + 5*1 345 base 7 = 147 + 28 + 5 345 base 7 = 180 base 10

OpenStudy (anonymous):

this part is a little confusing

jimthompson5910 (jim_thompson5910):

look at my second example

OpenStudy (anonymous):

hmm...okay maybe i get it now

jimthompson5910 (jim_thompson5910):

it's strange at first, I agree

jimthompson5910 (jim_thompson5910):

but with enough practice, it's not too bad

OpenStudy (anonymous):

i bet i will practice n get it

jimthompson5910 (jim_thompson5910):

ok great

OpenStudy (anonymous):

thanks :) u must be in like comp major or something...u r smart

jimthompson5910 (jim_thompson5910):

I took a bunch of computer science courses, but I'm actually a math education major

OpenStudy (anonymous):

That's great.

Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!
Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!