Elementary teachers and parents play the biggest role in a child's mathematical development, especially from Kindergarten through Fourth Grade. Time spent in school learning math or not learning math can never be replaced. Parents should make sure the elementary math teacher is knowledgeable and is a good teacher.
Parents can assist with developing a lot of the fundamental skills needed for children to succeed in math when they attend school. Parents can do things that will support the schools and hopefully the schools will do the rest.
The children also compete locally, state wide, and on the national level. The experience is invaluable. There are also other mathematical games and clubs that children can join that will help develop skills and are fun. Parents should contact their local school district or state level office of Gifted and Talented Programs for this information.
Use things around the house that they already know and love! : My son has a HUGE adoration for his Thomas Trains... he can tell you every single trains name, number and color. When we started working on recognizing numbers and colors, I tried to use posters, games, workbooks, etc that would help him learn to recognize them... all to no avail! One day, we were playing with his trains, and HE asked me what number one of the trains was. Bells went off in my head and I realized that I could cater his natural curiosity about his beloved trains, and still be 'teaching' him to recognize numbers at the same time!