Grimrock

please can u help me as im totally stuck on this.how is this done,i know to step on 123,65,65,87 but how.what do i do to get from 123 to 65 without going over same pressure plates.sorry if im a bit dim but this is really getting to me. thank you all

thank you but ive seen this.im still not sure how to do it,do i do something after each plate i step on or what. im missing something .thanks again