Maria ordered a certain number of televisions for the stock of a large store, paying $\mathrm{R} \$ 1994.00$ per television. She noticed that, in the total amount to pay, the digits 0, 7, 8, and 9 do not appear. What is the smallest number of televisions she could have ordered?
Let's say Maria ordered $n$ televisions, paying R \$ 1994.00 per television. The total paid is $1994 n$, and we know that in this multiple of 1994, the digits 0, 7, 8, and 9 do not appear. To limit the value of $n$, we observe that

$$
1994 n=2000 n-6 n
$$

If $6 n<300$, then the number $2000 n-6 n$ has 7 or 8 or 9 in the hundreds digit (try some examples, remembering that $2000 n$ ends with three zeros). Therefore, we must have $6 n \geq 300$, or $n \geq 50$.

Testing $n$ equal to 50, 51, 52, 53, 54, and 55, we get 99700, 101694, 103688, 105682, 107676, and 109670, but $n=56$ gives 111664. Thus, the smallest number of televisions Maria could have ordered is 56.