Relativistic momentum keeps the classical mass-times-speed idea but adds the gamma factor. In this toy ledger, mass 4 kg and speed 3 m/s would give 12 kg m/s classically, then multiplying by gamma 5/4 gives 15 kg m/s. Real momentum measurements depend on calibrated masses, speeds, reference frames, units, and uncertainty; these numbers are a pinned arithmetic model.
Relativistic momentum keeps the same speed but adds the checked gamma factor. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Classical momentum omits gamma
Mass 4 kg and speed 3 m/s would give classical momentum 12 kg m/s.
4⋅3=12
Relativistic momentum includes gamma
Multiplying by gamma 5/4 gives momentum 15 kg m/s.