I have 450 block to lay,how many bags do i need,and how much sand?

I would buy spec mix type S. morter 94lb.bags. this is easy to use just add water and mix it well then let stand for 15 min. and remix no water. If to wet add more morter and mix well. with this you dont need sand. the amout depends on the joint size standard is 1/2in. you should need about 10 to 15 bags