First, we make some observation:
January
- Has 7 letters,is the 1st month of the Year, and J is the 10th letter in the Alphabet=7110
February - Has 8 letters,is the 2nd month of the Year, and F is the 6th letter in the Alphabet= 826
March
- Has 5 letters,is the 3rd month of the Year, and M is the 13th letter in the Alphabet=5313
April
- Has 5 letters,is the 4th month of the Year, and A is the 1st letter in the Alphabet=541
May
- Has 3 letters,is the 5th month of the Year, and M is the 13th letter in the Alphabet=3513
June
- Has 4 letters,is the 6th month of the Year, and J is the 10th letter in the Alphabet= 4610
July
- Has 4 letters,is the 7th month of the Year, and J is the 10th letter in the Alphabet=4710
August
- Has 6 letters,is the 8th month of the Year, and A is the 1st letter in the Alphabet= 681
September
- Has 9 letters,is the 9th month of the Year, and S is the 19th letter in the Alphabet= 9919
Answer: September
9919