−

The keyboard's hyphen is short, low and misaligned; the minus sign U+2212 was cut for mathematics: the width of +, the axis of =. In a column of numbers the difference leaps out.

The mistake it corrects is a silent one: −5 °C with a hyphen looks like a dwarf dash; with U+2212 the negative number lines up with the sum beside it. The entity is −.

Wrong:  balance of -273.15   (hyphen: short, off-axis)
Right:  balance of −273.15   (minus: exact match for + and =)