A checked gradient predicts a signal at a measured distance. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Move partway along the gradient

Start from signal 6 and move 3 m along a gradient of 2 per meter.

23=62\cdot3=6
Signal prediction ledgerA distance along the checked gradient predicts a signal level.distance12

Add the gradient change to the start signal

The predicted midpoint signal is 12.

6+6=126+6=12
Signal prediction ledgerA distance along the checked gradient predicts a signal level.distance12