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Let $X_1,X_2,...$ be the digits in the base-$q$ expansion of a random
variable $X$ defined on $[0,1)$ where $q\ge2$ is an integer. For $n=1,2,...$,
we study the probability distribution $P_n$ of the (scaled) remainder
$T^n(X)=\sum_{k=n+1}^\infty X_k q^{n-k}$: If $X$ has an absolutely continuous
CDF then $P_n$ converges in the total variation metric to Lebesgue measure
$\mu$ on the unit interval. Under weak smoothness conditions we establish first
a coupling between $X$ and a non-negative integer valued random variable $N$ so
that $T^N(X)$ follows $\mu$ and is independent of $(X_1,...,X_N)$, and second
exponentially fast convergence of $P_n$ and its PDF $f_n$. We discuss how many
digits are needed and show examples of our results. The convergence results are
extended to the case of a multivariate random variable defined on a unit cube.