Nick’s father puts the money in a trust fund, and when Nick turns twenty-one he gives most of it away but buys some things for himself. He also sets up a scholarship fund in Mrs. Granger’s name.
Nick’s father is approached by Bud Lawrence, who wants to make money off of Nick’s word. His father puts the checks in the trust fund, where they grow to a substantial amount of money by the time he is twenty-one. He gives some of it to friends and family, and uses some to buy some things.
Nick’s father asks Bud to keep the money a secret because he doesn’t think Nick will be responsible with the money if he finds out.
If Nick knew, he’d probably stop mowing lawns and I’d never get him to save another penny. (ch 12, p. 83)
So Nick does not get access to the money until he is twenty-one. At that time, he gives some of it to his parents for a vacation and to his brother James.
After that, Nick went out and bought himself a fast new computer. And about ten new games. And a mountain bike. Then he tried to forget about the money, which is a hard thing to do. (ch 15, p. 96)
When Nick realizes that Mrs. Granger had been rooting for frindle all along, he is surprised that “by fighting against it, she had actually helped it along” (ch 15, p. 100)
Nick decides to use the rest of the money to set up a scholarship fund in her name, “established with one million dollars,” so that he can live a normal life and give back some of what she gave him (p. 103).
The reader is never told what happens to these checks that are put into Nicks's trust fund!