Positive and Negative Numbers
Every non-zero number has a sign: it is either positive (greater than zero, usually written with no symbol or a “+”) or negative (less than zero, written with a “-”). Zero itself is neither positive nor negative – it sits exactly at the boundary between them.
The “+” and “-” symbols we use today first appeared in print in the German mathematician Johannes Widmann's 1489 arithmetic textbook, originally as warehouse marks used by German merchants to note surpluses and shortages in shipments – a wonderfully down-to-earth origin for two of the most-used symbols in all of mathematics. It took a further two centuries or so for the symbols to become fully standardised as we use them today, for both signs and operations.
Positive, Negative, or Zero?
Any real number is exactly one of: positive (> 0), negative (< 0), or zero.
-14 is negative (less than 0). 6 is positive (greater than 0). 0 is zero – neither positive nor negative.
Combining Signed Amounts
4 − 9 = -5°C – the temperature has gone below zero.
Real-Life Application
- Bank accounts: a positive balance versus an overdraft (negative).
- Sea level: mountains are positive elevations; ocean trenches are negative.
- Sports: a golf score under par is often shown as negative.
Key Takeaways
- Every number is positive, negative, or zero – zero is neither.
- The + and - symbols began as 15th-century German merchants' warehouse marks.
- Combining positive and negative amounts (like temperature changes) is the everyday use of signed numbers.
Practice: Positive and Negative Numbers
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