Wattage calculation for resistors in series
Since resistors are in series, the current will be the same throughout the chain. Assuming that the voltage V across the string of resistors is constant, you can calculate the current \$I={V \over R_1+R_2 +R_3+ ...}\$. Power dissipated on each of the resistors: \$P_i=I^2R_i\$. If \$P_i\$ is less than the power rating of the resistor, it should dissipate the power without burning.

A string of N identical resistors in series each rated for P watts can dissipate \$NP\$ watts.