Interesting read for those that like to see where all the numbers showup. This was my favorite albeit a little reaching:
Assign each letter of the alphabet a number so that 1 is A, 2 is B, etc. up to 26 for Z. Then wrap back to the beginning so that 27 is A again, 28 is B, 29 is C, and so on.
4: The 4th letter in the alphabet is D
8: The 8th letter in the alphabet is H
15: If you add 4 + 8 + 15, you get 27 which wraps back to A.
16: 4 + 8 + 15 = 27, and 4 + 8 + 15 + 16 = 43. 27 + 43 = 70 which gives you a R.
23: 16 + 23 = 39, which is M.
42: 4 + 8 + 15 + 16 + 23 = 66, and 23 + 42 = 65. 65 + 66 = 131 which is an A.