One tool that can be used is Real numbers examples and answers.
A Real Number can have any number of digits either side of the decimal point. 120. 0.12345; 12.5509; 0.000 000 0001; There can be an infinite number of digits, such as 13 = 0.333 Why
There were a few questions that even this app was like, "What on earth am I looking at?" And never gave me an answer, which I don't blame it for, even so, it is still an extremely useful and convenient app that shall continue to use in the future.