When recounting the 10 generations from Adam to Noach, the years of their lives are written in the style of 1's, 10's and 100's place, e.g. ויחי ירד שתים וששים שנה ומאת שנה. Except for one exception, Breishis 5:5 - "ויהיו כל ימי אדם אשר חי תשע מאות שנה ושלשים שנה וימת". Any idea as to why?
My chavrusa found a העמק דבר (on that פסוק) that answers the question. He says that אדם and אברהם both have their years written in this way because they were רב פעלים, especially great in deeds, and so the fewer years are listed after the greater years to teach that in those fewer years they accomplished as much as they had during those many previous years. (He also says that there exceptions, such as שרה's years were written this way for a different reason that חז"ל have explained.)