This may help.
From ENF 23
http://www.cic.gc.ca/english/resources/manuals/enf/enf23-eng.pdf6.4. Day
For the purpose of calculating the number of days to comply with the residency obligation in A28(2)(a), a day includes a full day or any part of a day that a permanent resident is physically present in Canada. Any part of a day spent in Canada, or otherwise in compliance with A28(2)(a), is to be counted as one full day for the purpose of calculating the 730 days in a five-year period.