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Irrational Numbers

An irrational number is a number that can't be expressed by a fraction having integers in both its numerator and denominator. While their existence was once kept secret from the public for philosophical reasons, they are now well accepted, yet still surprisingly hard to prove on an individual basis. Please post all questions about irrational numbers, including the famous examples of π, e, and √2, into this category.

3,962 Questions

Is 21 out of 71 rational or irrational?

21/71 is rational. Rational numbers are numbers that can be written as a fraction. Irrational numbers cannot be expressed as a fraction.

Is 6.23 rational?

Yes, 6.23 is rational because it has terminating decimal. And it can be expressed in simple fraction, in the form of p/q, as 623/100, 6320/1000 etc.

It is to be remember that p and q are integers and q is not equal to 0.

What was Georg Bernard Riemann's example of a function that is continuous at zero and irrational values but discontinuous at positive and negative rational numbers?

f(x)=0 if x=0 or x is irrational, f(x)=1/q if x=p/q "in lowest terms", i.e., gcd(p,q)=1.

To see that it satisfies the claims, you simply need to verify that the limit as x approaches p is 0 for all p, which is pretty easy. From this both claims follow.

What are the first 300 decimals of pi?

3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679

82148086513282316647093844609550582231725359408128

48111745028410270193852110555964462294895493038196

44288109756659334461284756482337867831652712019091

45648566923460348610454326648213393607260249141273


Broken into chunks of 50.


If you wanted to know these for memorisation, there are thousands of results from searching "digits of pi", some of which can display up to the first million digits.

Is 5.284 a rational number?

Yes. It can be written as the fraction 5,284/1,000 .

What is square root of 2?

The square root of two is an irrational number that when multiplied by itself gives you the value 2. It is approximately equal to 1.4142135623730951.

What is 404404440 an irrational number?

No because all integers or whole numbers are rational

Define and give example of irrational numbers?

an irrational number is any real number that cannot be expressed as a ratio a/b, where a and bare integers, with b nonzero, and is therefore not a rational number.

Informally, this means that an irrational number cannot be represented as a simple fraction. Irrational numbers are those real numbers that cannot be represented as terminating or repeating decimals. As a consequence of Cantor's proof that the real numbers are uncountable (and the rationals countable) it follows that almost all real numbers are irrational.[1]

When the ratio of lengths of two line segments is irrational, the line segments are also described as being incommensurable By Paul Philip S. Panis

Can an irrational number be used as an integer?

No because an integer is a whole number without any decimals whereas an irrational number is a decimal number that can't be expressed as a fraction as for example the square root of 2.

Does every non-terminating decimal represent an irrational number?

No; if the non-terminating decimal repeats then it represents a rational.

Examples:

  1. 0.3333... = 1/3
  2. 0.428571428571... = 3/7
  3. 0.181818... = 2/11

Why is negative 3 rational?

Because it can be expressed as an improper fraction in the form of -3/1 and so therefore it is a rational number

Are irrational numbers always integers?

No. An irrational number is one that is not a rational number. A rational number is once that equals one integer divided by another. So an irrational number cannot be represented by one integer divided by another integer, so it cannot be an integer!