What is 5 + 4?

The sum of 5 + 4 is equal to 9. This is a basic arithmetic operation where you add 5 and 4 together. Addition is a mathematical operation that combines two or more numbers to give a total or sum. In this case, adding 5 and 4 results in 9. Addition is commutative, which means that changing the order of the numbers being added will not affect the sum. So, 5 + 4 is the same as 4 + 5, both equal to 9.