Answer:
28 + 31 + 29 + 28 = 116 days
Explanation:
"30 days has September, April, June, and November. All the rest have 31. Except February, which has 28, and in leap year 29."
If you haven't memorized that yet, do it now. You'll use it all your life.
So now just break it down into steps:
How many days are left in December? You now know it has 31 days, so 31 - 3 = 28. Count them out on your fingers if you want, but make sure you understand that.
How many days in January? Refer to the rhyme: 31
How many days in Feb? They tell us it's a leap year, so 29.
And now how many days from March 1st to the 28th? 28
Now just add them up: 28 + 31 + 29 + 28 = 116 days
Here's a shortcut that's just a tiny bit easier:
If go from Dec 3rd to Jan 3rd, you know that must be 31 days, because Dec has 31 days. (Like above, you could count 28 days to the 31st, then add 3 more days to the 3rd of January. Or just do that in 1 step.)
⇅Take the time to understand that.⇵ Look at a calendar and count out the days if you need to.
Then go from Jan 3 to Feb 3, and that's 31 days, because January has 31 days.
Then go from Feb 3 to March 3. Remembering that Feb has an extra day in a leap year, that's 29.
Then from March 3rd to the 28th is 25 days.
31 + 31 +29 + 25 = 116, same answer as before.
I prefer using that method, but either way works.