With area fixed, the normal stress follows the force. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Keep the area fixed before changing force
This contrast holds the area marker steady. Only the force input is larger than the base case.
F=24NA=3m2
Doubling force doubles stress in the table
The area column is unchanged. The force and stress columns scale together in exact integer steps.
F12N24N36NA3m23m23m2σ4Pa8Pa12Pa
Doubling force doubles the stress when area stays fixed
The area is unchanged, so the checked stress doubles with the force.