Final answer:
To estimate 809 ÷ 9, we round up to 810 and divide by 9 to get a quotient of 90, which is an overestimate.
Therefore, the correct answer is: option A). 90; overestimate
Step-by-step explanation:
To estimate the quotient 809 ÷ 9, you can round 809 to the nearest multiple of 9 that is easy to divide in your head, such as 810.
Now, 810 divided by 9 equals 90.
This is because 9 times 90 equals 810.
So, the estimated quotient is 90. Since we rounded up from 809 to 810, our estimation will slightly be over the actual quotient.
The actual quotient of 809 ÷ 9 is a little less than 90.
Therefore, the estimation of 90 is an overestimate.