How do you write 782% as a fraction or mixed number in simplest form?

782% is just 782/1000. In decimal form, this works out 0.782. Now both the numerator and denominator look like they have common factors of 2. When reduced, that takes us to 391/500. That's about as simple as this can get! This cannot be written as a mixed number, the reason being that the numerator is not larger than the denominator, so it's just left as a fraction.