# Tag Info

In a nutshell, the number of qubits in the top register directly corresponds to the number of bits of precision to which $x/T$ approximates $s/r$, and we need enough precision to be able to determine $s$ and $r$ given $x/T$. For example, if $s=1$ and $r$ is large, then we cannot afford to confuse $1/r$ with $1/(r+1)$, say. In more detail, think about any ...