my problem (teaching Matlab) uses the underscore in the problem statement

ind_p1 = t>=0 & t<1;

ind_p2 = t>=0 & t<2;

ind_p3 = t>=-1 & t< 0;

ind_p4 = t>=0 & t<3;

ind_p5 = t>=3 & t< 4;

ind_p6 = t>=1 & t < 2;

ind_p7 = t>=0 & t < 10;

ind_p8 = t>-10 & t<=0;

ind_p2 = t>=0 & t<2;

ind_p3 = t>=-1 & t< 0;

ind_p4 = t>=0 & t<3;

ind_p5 = t>=3 & t< 4;

ind_p6 = t>=1 & t < 2;

ind_p7 = t>=0 & t < 10;

ind_p8 = t>-10 & t<=0;

when I try to generate hardcopy of the problem set I get the error

First error in TeX log is:

! Missing $ inserted. <inserted text> $ l.237 \leavevmode\\\relax ind_ p1 = t>=0 & t<1; I've inserted a begin-math/end-math symbol since I think you left one out. Proceed, with fingers crossed. Is it possible generate hardcopy with an underscore? I didn't see anything in the forum search.