theorem Th97:
  n|^3 <= 98 implies n <= 4
  proof
    assume
A1: n|^3 <= 98;
A2: n|^3 = n*n*n by POLYEQ_5:2;
    assume n > 4;
    then
A3: n >= 4+1 by NAT_1:13;
    then n*n >= 5*5 by XREAL_1:66;
    then n*n*n >= 25*5 by A3,XREAL_1:66;
    hence thesis by A1,A2,XXREAL_0:2;
  end;
