When you add a number to another number the result is their sum
Addend is the number being added to another number in an addition problem to derive a sum.
An addend
ADDITION
addend
It is called the digit.
That would be an addition problem such as 2+3=5 5 would be the sum.
A natural number is doubled when added to its reciprocal. Find that number!
5 or -6.
7 Or -8
The total number of protons.
7