The total number of slokas in vedas altogether is 100000 (states in vishnu purana )
How the one Veda was divided into four is explained more fully in the following quote from the Vishnu Purana: There was but one Veda (in the oral tradition), the Yajur Veda. The first Veda in four parts consisted of 100,000 stanzas, in which there were ten kinds of sacrificial rituals. Dividing it into four parts, Vyasa instituted the sacrificial rite that is administered by four kinds of priests, in which it is the duty of the Adhvaryu priests to recite the prayers (Yajush, or direct the ceremony); of the Hotri priests to repeat the hymns (Richas); of the Udgatri to chant other hymns (Sama); and of the Brahmana priests to pronounce the formula called Atharva. Then the great Muni, having collected together the hymns called the Richas complied the Rig Veda. With the prayers and directions termed the Yajushas he formed the Yajur Veda. With those called the Sama, he formed the Sama Veda. And with the Atharvas he composed the rules of all the ceremonies suited to kings, and the function of the Brahmana agreeably to practice in the Atharva Veda. This was the original tree of the Vedas, having been divided by him into four principal stems, soon branched out into an extensive forest of knowledge. (Vishnu Purana, Book Three, Chapter Four)
Now the question. Des anybody know any puranic reference to state number of slokas in each veda(Rig, Yajur, Sama & Atharva).