To solve the first equation \(20 \times ? = 10,000\), you can find the missing value by dividing both sides by 20:
\[ ? = \frac{10,000}{20} = 500 \]
For the second equation \(20 \times 400 = ?\), you multiply:
\[ ? = 20 \times 400 = 8,000 \]
So, the answers are:
- \(? = 500\)
- \(? = 8,000\)