My question is probably best illustrated with an example:

Four 2.25 hp electric motors were used to propel the vehicle.

Is that correct? I feel like it can't be, but my friend is saying otherwise. I'm also finding contradictory rules on the internet so I'm not sure. I think it should be:

Four 2.25-hp electric motors were used to propel the vehicle.

or Four 2.25-hp-electric motors were used to propel the vehicle. ?

I know similar questions have been asked but they were simpler than mine. Hopefully someone can help me. Thanks.

2 Answers 2


What you're saying is perfectly fine as it's clear that the electric motors are 2.25 hp each.

If you want to avoid confusion though, you could use the word "separate"

Four separate 2.25 hp electric motors were used to propel the vehicle.



  1. detached, disconnected, or disjoined.
  2. unconnected; distinct; unique: two separate questions.
  3. being or standing apart; distant or dispersed: two separate houses; The desert has widely separate oases.
  4. existing or maintained independently: separate organizations.
  5. individual or particular: each separate item.

I don't think there is any need for the dashes '-' to join 2.25 hp and electric, but because the unit for horsepower is lower case hp is does look a little clumsy.

It may be clearer is you spell out horsepower in full as 2.25 horsepower electric motor

Depending on the layout of the vehicle and it's motors you could reword the sentence to

The vehicle is/was propelled by a 2.25 horsepower electric motor at each wheel.

then there is no issue with plurality either.

  • Yes, that's one of the functions of Passive -- to avoid such situations where the details don't matter. Note (1) that the focus -- the new information -- in the sentence continues to be the four two and a quarter horsepower motors, and (2) that the end of the sentence is as prominent a position for the focus as the beginning. Apr 16, 2014 at 15:41

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