Correct spelling for the English word "ks" is [kˌe͡ɪˈɛs], [kˌeɪˈɛs], [k_ˌeɪ_ˈɛ_s] (IPA phonetic alphabet).
* The statistics data for these misspellings percentages are collected from over 15,411,110 spell check sessions on www.spellchecker.net from Jan 2010 - Jun 2012.