A calibrated cantilever is easier to read when deflection changes across several checked cases. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Two metres of deflection reads six newtons
Keep cantilever stiffness at 3 newtons per metre. Deflection 2 metres gives force 6 newtons.
3⋅2=6
Three metres gives nine newtons on the same cantilever
The stiffness stays 3 newtons per metre while deflection rises to 3 metres, so the force reads 9 newtons.
3⋅3=9
Four metres gives twelve newtons
At deflection 4 metres, the same calibration gives 12 newtons. Three rows make the force-meter slope readable.