Beatriz adores odd numbers. How many numbers between 0 and 1000 can she write using only odd digits?
As each digit is odd, we have:

- five possibilities for numbers with one digit: 1, 3, 5, 7, and 9;
- for numbers with two digits, we have five possibilities in the units place and five in the tens place, totaling $5 \times 5=25$ possibilities;
- for numbers with three digits, we have five possibilities in the units place, five in the tens place, and five in the hundreds place, totaling $5 \times 5 \times 5=$ 125 possibilities.

Thus, Beatriz can write $5+25+125=155$ numbers with all digits being odd.