  We construct certain elements in the integral motivic cohomology group
$H^3_{{\cal M}}(E \times E',\Q(2))_{\ZZ}$, where $E$ and $E'$ are elliptic
curves over $\Q$. When $E$ is not isogenous to $E'$ these elements are
analogous to `cyclotomic units' in real quadratic fields as they come from
modular parametrisations of the elliptic curves. We then find an analogue of
the class number formula for real quadratic fields. Finally we use the
Beilinson conjectures for $E \times E'$ to deduce them for products of $n$
elliptic curves. A certain amount of this paper is expository in nature.
