  We investigate the following generalisation of the 'multiplication table
problem' of Erd\H{o}s: given a bipartite graph with $m$ edges, how large is the
set of sizes of its induced subgraphs? Erd\H{o}s's problem of estimating the
number of distinct products $ab$ with $a,b \le n$ is precisely the problem
under consideration when the graph in question is the complete bipartite graph
$K_{n,n}$. In this note, we prove that the set of sizes of the induced
subgraphs of any bipartite graph with $m$ edges contains $\Omega(m/(\log
m)^{12})$ distinct elements.
