I think your idea will work wonderfully and see no reason for it not to be. I suggest keeping jars of buttons, bags of rocks, etc around the house and garage. You could set 45 pebbles on a piece of paper, or in a shoe box. To play with throughout the day, Stitch 78 buttons on a piece of cloth etc. Always "check" to make sure all the objects are there in the end by counting or skip counting.
Also, print outs of various pictures, etc and making quantity books and such is a good idea and might be a lot of fun. you might try making the books on clear contact paper, so you just stick and press and fold over another piece of contact paper,
. I got the idea from a blog, since the child hated glue with a passion his mom let him do "sticky" art on contact paper.