There is no special symbol to indicate an irrational number.
To indicate something you don't understand
The symbol that you describe seems to be the greek letter Phi. It is normally used to indicate a variable that is an angle, just as x is used to indicate a variable that is a numeric quantity.
Rectangles
An equality symbol such as =
The "^" symbol is used in proofreading marks to indicate that a letter should be lowercase.
The proofreading symbol that looks like a circumflex is called a caret. It is used to indicate where an additional or corrected word should be inserted in a text.
The backslash proofreading symbol is used to indicate a space that should be deleted, especially in typesetting or formatting work. It signifies that the space preceding the backslash should be removed to ensure proper formatting and alignment of the text.
There is no backslash proofreading symbol in existence, for more information on all the proofreading symbols, refer to this page: http://webster.commnet.edu/writing/symbols.htm
There is no backslash proofreading symbol in existence, for more information on all the proofreading symbols, refer to this page: http://webster.commnet.edu/writing/symbols.htm
The proofreading mark for lowercase is a caret symbol (^) placed below the letter that needs to be lowercase.
The symbol used to indicate that something is to be inserted in a document is called a caret symbol. It looks like a small V-shaped mark (^) and is commonly used in editing and proofreading to show where additional text should be added.
Put a mark through the capitalized letter.
The proofreading mark for an error in a sentence would be a caret (^) to indicate where the correction should be inserted.
The symbol used to indicate that copy has been repeated in a sentence is called a caret, also known as a proofreading mark. It looks like a small "V" shape (^) and is placed underneath the repeated word or phrase.
The proofreading mark DS stands for "delete space." It is used to indicate that there is an unnecessary space that should be removed between two words or sentences.
In proofreading it is customary to use the " ^ " symbol to specify that a letter or wrod is missing from the scentence. You want to write the word or letter above the "^" sign to specify what the missing word or letter is.