Can someone write an irrational number?

Just any one.

An irrational number is a number that cannot be expressed as a fraction.

Take pi for example:
pi = 3.14

You cannot express that as a fraction/ratio.

A rational number, is the opposite, you can express it has a simple fraction.

example of rational number:
1.5 can be written as 3/2

more information:
https://www.mathsisfun.com/irrational-numbers.html

π is indeed an irrational number ,

but Don Ho said
π = 3.14, which is not true, since 3.14 = 314/100
or 157/50 and that would be a rational number

all radicals that are not perfect squares, are also irrational number
e.g. √5

Yes, someone can write an irrational number. An irrational number is any real number that cannot be expressed as a fraction of two integers. Examples of irrational numbers include √2, π (pi), and e.

To write an irrational number, you can simply write the symbol or representation of the irrational number. For example, to write √2, you would write the square root symbol (√) followed by the number 2. Similarly, to write π, you would write the Greek letter "π". Writing the irrational number e is as simple as writing the letter "e". These notations represent well-known irrational numbers.

It's important to note that irrational numbers can have infinite decimal places without repeating or terminating, which makes them non-representable as exact values.