How many thoughts has a person had in their life. In my case it would be hard to say. There are many shades and degrees. I talk inside myself all the time, mentally and usually in English. Aside from my articulated statements I have many feelings and wonderings that would be hard to quantify. What about the reader? DE
No matter what the quantity, it would be fewer than the milliseconds-long intervals of extrospective and introspective change which the brain discerns and represents with its experiences. Those snapshots are too short to fit a semantic unit of linguistic thought in, as well as even a non-lingual completed recollection and feeling that could express significance of some kind.
average human lifespan = 71 years (http://www.who.int/gho/mortality_burden_disease/life_tables/situation_trends/en/) average thoughts per day = 60,000 (source: http://www.huffingtonpost.com/bruce-davis-phd/healthy-relationships_b_3307916.html) thoughts per lifespan = 71 years * 365 days * 60,000 thoughts = 1,554,900,000 thoughts of an average human being in lifespan