Posted by **Eleonora** on Tuesday, September 8, 2009 at 10:52pm.

Is .121221222122221... (the pattern in this number continues forever) a rational number or irrational number? Why?

(my research is listed in a previous question post, but I'm stuck!!! Please help!) :-)

- Math -
**MathMate**, Tuesday, September 8, 2009 at 11:07pm
Each term 0.12, 0.00122, 0.000001222, 0.00000000012222, ...

is a rational number. When continued forever and added together, it does not have to be a rational number.

Another example:

1, 1/3, 1/5, 1/7, 1/9, ... are all rational numbers.

If we look at the sum

S = 1 - 1/3 + 1/5 - 1/7 + 1/9 - ....

S equals π/4, a known irrational number.

In fact, a non-recurring decimal number is considered an irrational number.

See:

http://en.wikipedia.org/wiki/Irrational_number

- Math -
**camy**, Wednesday, September 9, 2009 at 1:00am
you have to put in the division,addition,sub., or whatever to answer this...(44,8,74,21,4)=10

- Math -
**MathMate**, Wednesday, September 9, 2009 at 7:41am
Camy,

It is not a good idea to piggyback a question on someone else's question. It may get ignored or overlooked.

As there are no replies yet, I suggest you repost the question as a new thread.

Thank you.

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