You are not doing maths here. You are writing a program. The program will calculate the answer, not you. If you tell it to add 1 and 1, ie 1 + 1, you don’t need to tell it that the answer is 2, it will do that calculation for you.
The examples are explaining what the remainder operator does, in maths terms. So if it was explaing what “add” was,
The addition operator + adds two numbers.
Example
1 + 1 = 2
But that what the computer does for you, if you’re asked to set the variable add to the value of 1 + 1, that’s
var add = 1 + 1
Not
1 + 1 = 2
Which makes no sense: = in the programming language you’re learning means “assign the value on the right hand side to the name on the left”, you are not writing equations.