Answer: 20,000
Step-by-step explanation:
We can estimate the product of 5 and 4,257 by multiplying 5 by 4,000
5 * 4,000 = 20,000
The product of 5 and 4,257 is about 20,000
The real answer (not an estimate)
21,285
That is around 20,000 so we are correct