Values such as integers can have fixed number of bits i.e they are fixed width value. This means they can accommodate only range of values. In case of operations trying to create a integer larger than its max possible value, the value will overflow i.e it will end being 0. Some libraries provide a way of handling large numbers like Python, Ruby, etc. It is able to handle it by storing large numbers in array of integers which are parts of large number. Operations like addition are then performed by adding these parts of two numbers together to create a new large number. This will be a lot slower operation than small numbers addition.