"The Oppenheim conjecture proved in 1986 asserts that for a nondegenrate indefinite irrational quadratic form Q in in n>2 variables the set Q(Z^n) is dense.

In the talk I will duscuss the quantiative version of this conjecture. In particular I will describe recent results in the case of signature (2,2) and some corollaries about eigenvalue spacings on flat 2-tori."