How many whole numbers have a square root whose units digit is 4? I am completely lost. I never learned this in school

Question

In this question the units digit is 4. What is a units digit and how do i find the answer to this problem? I want to know the process so I can solve these problems in the future.

Answer 1

An unlimited number of numbers have a square root whose digit is 4. 

Some of them:

16, 196, 576, 1156, ... 

Can you see the pattern and derive a rule?