January => 31
 February => 28 (29)
 March => 31
 April => 30
 May => 31
 June => 30
 July => 31
 August => 31
 September => 30
 October => 31
 November => 30
 December => 31
 
Have you noticed that seven (7) months of the year have 31 days  January, March, May, July, August, October, December. These are Months 1, 3, 5, 7, 8, 10, 12. (Note the almost alternate nature!)
Only four months have 30 days  April, June, September, November. Months 4, 6, 9, 11. (Again, almost alternate!)
February has 28 days except for leap years when there are 29 days (once every 4 years).
More broadly, there are only two occasions where there are consecutive months of 31 days  December/January and July/August.
What emerges is a pattern of alternate size similarity!
Want to find the number of days in a specific consecutive group of months?
 Select Start month.
 Select number of months to accumulate.
 Press the 'Calculate Number Of Days' button (when it appears !).
