Why temperature conversion needs more than a multiplication
Most unit conversions — length, weight, volume — are a simple multiplication, because every scale shares the same zero point. Temperature is different: 0°C is not the same physical temperature as 0°F, so converting between them requires both scaling and shifting the number, not just multiplying it.
°F = °C × 9/5 + 32
K = °C + 273.15
Kelvin avoids negative numbers entirely for any physically realistic temperature, since 0 K represents absolute zero — the coldest temperature theoretically possible — which is why it's the standard scale in scientific contexts despite being unfamiliar for everyday use.