Says at the top of the paper estimate the quotient for the following problems

All you have to do is round the numbers and then divide. For example, here are the first 2 answers.

b. 2,000 divided by 20 = 100
c. 8,000 divided by 40 = 200

So if you had 3,861, you would round that to 4,000, and round 59 to 60.
So basically, in the 100's, if it is 0-4, round down. (Ex. 4,371=4,000), and if it is 5-9, round up. (Ex. 7,920=8,000), then just divide the two numbers.