Can N be any number when divided by infinity?

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Discussion Overview

The discussion centers on the mathematical treatment of infinity, particularly in the context of dividing a number N by infinity. Participants explore whether N can be any number when divided by infinity and the implications of treating infinity as a number in arithmetic operations.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant claims that N divided by infinity equals zero, suggesting that N can be expressed as zero multiplied by infinity.
  • Another participant challenges this by stating that arithmetic operations involving infinity are not valid and that N divided by infinity is undefined.
  • It is argued that infinity is not a number and cannot be used in the same way as finite numbers in calculations.
  • A participant references limits, stating that the limit of N divided by x as x approaches infinity equals zero, but emphasizes that the expression zero multiplied by infinity is undefined.
  • Concerns are raised about the treatment of zero and infinity in mathematical structures, noting that zero does not belong to certain number groups and cannot be multiplicatively inverted.
  • Clarifications are made regarding the definition of limits, with one participant asserting that while the limit of zero multiplied by x as x approaches infinity is defined and equals zero, zero multiplied by infinity itself remains undefined.
  • Another participant reiterates that infinity and infinitesimals should not be treated as standard numerical values for arithmetic operations.

Areas of Agreement / Disagreement

Participants generally disagree on the treatment of infinity in arithmetic operations, with some asserting it can be treated like a number and others firmly stating it cannot. The discussion remains unresolved regarding the implications of these differing views.

Contextual Notes

Limitations include the ambiguity surrounding the definitions of infinity and zero in various mathematical contexts, as well as the unresolved nature of certain mathematical operations involving these concepts.

gokhul
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Let N be any number
N÷∞=0
Cross multiplying
N=0*∞
Any number multiplied by zero is zero
Even infinity is a number but it is large
So
N = 0
 
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Is my assumption correct
 
No.

You cannot perform arithmetic operations on infinity.

More particularly, N÷∞= undefined.
 
Infinity is not a number. You can't use it like that.
$$
\lim_{x \rightarrow \infty} \frac{N}{x} = 0
$$
##
\lim_{x \rightarrow \infty} 0 \times x
## is undefined.

Correction: ##0 \times \infty## is undefined.
 
Last edited:
You assume that you can handle zero and infinity as numbers. As been said infinity isn't a number. 0 is a number but it doesn't belong to the halfgroup of ℕ or ℤ or group of ℚ or ℝ or ℂ with multiplication as group operation. It simply does not exist in there and therefore cannot be multiplicatively inverted.
 
Last edited:
[Edit: removed quote of Dr. Claude's original]

##
\lim_{x \rightarrow \infty} 0 \times x
## is defined and is equal to zero. However, that does not mean that ##0 \times \infty## is defined.
 
Last edited:
jbriggs444 said:
You may have a typo there.
##
\lim_{x \rightarrow \infty} 0 \times x
## is perfectly well defined and is equal to zero. However, that does not mean that ##0 \times \infty## is defined.
Yes. That was botched cut and paste. Thanks.
 
Infinity and the infinitesimal cannot be treated as straight up values for arithmetic operations, infinity is not a number you can reach. Defined by the limit as values for x gets bigger and bigger in contrast with constants in the expression. Just like what DrClaude said.
 

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