Answer
$f_1=440Hz$
$f_2=880 Hz$
$f_3=1320 Hz$
$f_4=1760 Hz$
Work Step by Step
The frequencies of the harmonics for a string that is fixed at both ends are given by equation 11-19b.
$$f_n=nf_1$$
The first four harmonics are:
$$f_1=440Hz$$
$$f_2=2 \times 440Hz=880 Hz$$
$$f_3=3 \times 440Hz=1320 Hz$$
$$f_4=4 \times 440Hz=1760 Hz$$