math question easy for smart people please help! 10 points!?

Question

an addition table for a subset of real numbers is shown below. which number is the identity element?

EXPLAIN...watz an identity element..please explain thoroughly

+ 0 1 2 3
________
0 | 0 1 2 3
1 | 1 2 3 4
2 | 2 3 4 0
3 | 3 4 0 1

Answer 1

Identity element is what number you can perform certain functions with to stay the same number

The identity element for addition is 0 as x + 0 = 0 + x = x
The identity element for multiplication is 1 as x * 1 = 1 * x = x

Yours is an addition table, so your answer is 0

Answer 2

The identity element is 0.
Basically an identity element under addition
for a table like this is an element e such that
a + e = a for every element in the table.
Here 0 fulfills this requirement, as you can
see by looking at the top row.

Answer 3

Whenever you add the identity element is 0. When you multiply it is 1.