How many...

How many 42 watt 6500 would i need for 2-3 plants? how many 42 watt 2500 would i need for flowering

Really depends on how you are going to hang them, how big the space is you are growing, if they are going to have a reflector, and if there is reflective paint/material around the plants. That said, I would say at least 2 6500k's per plant for veg, and at least 2 2500k's for flower.