MFRACTION

MFRACTION(x;p;m) returns the period within a month to which date-time value x belongs; p is the length of the period (e.g. 5 for pentade, 10 for decade), and m is the starting month (default 1). The period p can range from 1 to 31. Setting a period of 31 gives the month number. Alternatively, using a period of 1 calculates a day number within the year which will be the same for each day-month combination, whether or not this is a leap year. This differs from the NDAYINYEAR function, because MFRACTION adjusts for the months. So, starting counting from January, MFRACTION(x;1;1) always gives 1st March as day 61 in the year. With NDAYINYEAR, 1st March is the 61st day in a leap year, but only the 60th day in other years.