grammatical number - Singular or plural for seconds

For numbers of seconds, is it smaller or equal to 1 we use second, larger than 1 we use seconds?

For example:

0 second
0.5 second
1 second
1.5 seconds

Answer

SOME of the rules around 1 are:

• 
  
  

  "X somethings" when X is not 1

  
  


• 
  

  For 1 and 0 amounts with decimals pronounced "0 point Y" and "1 point Y", it is somethings:
  0.5 somethings, 0.1 somethings, 1.5 somethings, 1.1 somethings

  
  


• 
  

  For quantifications ending on a something, we have half a something, a quarter of a something because it is still relative to 1 (or a)

  
  

The same is the case for time, weight, money and other quantifications.

• 1 second/kilo/dollar


• half a second/kilo/dollar


• a third of a second/kilo/dollar


• 
  

  a quarter of a second/kilo/dollar - note a quarter (dollar) is one coin in the US.

  
  


• 
  

  0 seconds/kilos/dollars

  
  
  


• 0.5 (zero point five) seconds/kilos/dollars


• 0.1 (zero point one) seconds/kilos/dollars

For the rest of the rules and exceptions and possibly perceived rules, have a read of the answers to Is -1 singular or plural?