The Vajrasattva mantra is known as the "100-syllable mantra" because of that many Sanskrit syllables. In the Japanese tradition, the mantra has the same name (HYAKU JI MYO), however their pronunciation of the Sanskrit gives 121 syllables. The following is my version of the translation into English (not "transliteration"), based on the published version by Jeffrey Hopkins in "Kalachakra" p.403, and it yields 92 syllables:
OM VAJRASATTVA, RESIDE IN ME, I'LL KEEP THE SAMAYA. MAKE ME STRONG, MAKE ME SATISFIED, MAKE ME FULFILLED, MAKE ME COMPASSIONATE, GRANT ME ALL THE SIDDHIS, MAKE MY MIND VIRTUOUS IN ALL ACTIONS. HUM! HA HA HA HA HOH!
VAJRA OF ALL THE BLESSED TATHAGATAS, DO NOT ABANDON ME. INDIVISIBLY UNITE ME WITH ALL THE GREAT SAMAYA BEINGS. AH! HUM! PHAT!