Bernardo B. Terrado writes:

It's about Homophonic substitution and map E to 17,19,23,47,64 map A to 8,20,25,49 map R to 1,29,65 map T to 16,31,85 but otherwise the ith letter maps to the 3ith letter MANY A SLIP TWIXT THE CUP AND THE LIP will become 3608397220543324451666246931852117066045253909162147332445

My question is what/how did they represent the other letters like L (etc.) coz I've tried to map them and yet I still can't understand I even wrote A to Z then map them to 1 to 99, I still can't figure it out.

That's the "otherwise" rule right after the four "maps". If the 2-digit number is divisible by 3 (like the first "36"), divide it by 3 and count that many letters through the alphabet starting with A. The 12th letter (0-origin) is M, so 36 corresponds to M and L corresponds to 33. That particular example doesn't use the ciphertext space very efficiently: only 41% of the available 2-digit numbers are used. If you must use a homophonic, I'd suggest a 100-letter pangram, which gives a reasonable distribution of letters, full coverage of the alphabet, and some chance of remembering the thing without carry incriminating documents. -- Jim Gillogly Sterday, 29 Winterfilth S.R. 1998, 17:38 12.19.5.11.2, 13 Ik 15 Yax, Sixth Lord of Night