Bear is correct of course, there were packs of square you could get, they were usually in Dry Goods stores or 5&Dime, or in fabric stores next to the premarked embroidery squares, or even in the back of magazines. I had a thrift store find quilt that was a pack or two of bright 70s posies.
But pre-cuts as we know them now are largely from the last 20 years.
edit: PS, Dina your math does sound better to me. I was counting squares and not triangles so I think you are right on the money!