How many possible pairs of number factors does c have in the fallowing trinomial?

x^2+bx+36

X^2 + (m + n) x + m*n = (x + m) (x + n);

We have m*n = 36 and m + n = b;

1*36 = 36; m = 1; n = 36; the factors are (x + 1), (x + 36)

2*18 = 36; m = 2; n = 18; the factors are (x + 2), (x + 18)

3*12 = 36; m = 3; n = 12; the factors are (x + 3), (x + 12)

4*9 = 36; m = 4; n = 9; the factors are (x + 4), (x + 9)

6*6 = 36; m = 6; n = 6; the factors are (x + 6), (x + 6)

There are 5 pairs of number factors.