Final answer:
To find the unknown factor that, when multiplied with 34, gives 680, you perform the division 680 divided by 34, which results in 20. So, the unknown factor is 20.
Step-by-step explanation:
The question asks to find the number that, when multiplied by 34, produces the partial product of 680. To solve this, we divide the partial product by one of the known factors.
The equation to calculate this is: 680 ÷ 34 = ?
Performing the division we get:
680 ÷ 34 = 20
Therefore, the other factor is 20.