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Dears,

Please let me know which is used when?
One day's leave OR one days leave OR one days' leave?

Please let me know use of each (all 4) one day* patterns i.e.

one day's,
one days ,
one days' and
one day

Thanks,
CM
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You can use these:

Please grant me one day's leave of absence on March 1st.
Please grant me a one-day leave of absence on March 1st.
Please grant two days' leave of absence on March 1st and 2nd.
Please grant me a two-day leave of absence on March 1st and 2nd.
Comments  
Teachers: We supply a list of EFL job vacancies
I would say either:

one-day leave

or:

one day's leave
One day