Rob says all numbers have an even number of factors marcia says some numbers have an odd number who is correct

Marcia is correct.

Step-by-step explanation:

We are given that,

Rob states that 'all numbers have an even number of factors'.

Marcia states that 'some numbers have an odd number of factors'.

Let us consider the number 36. Now, it is given that,

1 × 36 = 36

2 × 18 = 36

3 × 12 = 36

4 × 9 = 36

6 × 6 = 36

Since, the repeated factor is counted only once. So, the factors of 36 are given by 1, 2, 3, 4, 6, 9, 12, 18 and 36.

This gives us that 36 has 9 factors and so, it has odd number of factors.

Hence, Marcia is correct.