5,660 kg of ore is needed
first find how much one gram of gold needs (how much ore) which is 200 kg of ore. Multiply that number 28.3. Because we are finding how much kg, we don't need to convert the answer to grams.
5660kg of ore must be mined to produce an ounce of gold.
If we use long multiplication to do 200x28.3 and evaluate the answer, it is 5660.