What is the maximum load that can be applied to

For a steel bar deformation begins at 400MPa it has a modulus of elasticity of 207GPa.a) What is the maximum load that can be applied to a cylindrical specimen 10mm diameter and 60mm long without plastic deformation?b) What is the maximum length it may be stretched to without plastic deformation?I am in ENGR-250 engineering materialsI think I got part a down. I multiplied (10mm)*(60mm) = 600mm = .00060m^2 then I took 400MPa = 400×10^6GPa and multiplied the GPa with the m^2.I don’t know how to start part b.