what is the estimated quotient of 2184 divided by 3.9?

Question

This is a multiple choice question and the alternatives are as follows : a. 2000, b. 500, c. 525 and d. 2. Please help me choose the correct answer.

Answer 1

Using 4 in place of 3.9, 2100 / 4 = 525.

Bingo!

Answer 2

To estimate, find "compatible numbers" [that is, numbers that are approximately the same as the given values, but which make the problem easier (thus, also saving time).  For example, "What is 2.054321 + 1.906789 ?"  Now, had the question been "What is 2 + 2," you would have known the answer immediately.  If you want to spend the time, you may verify your estimate by performing the exact calculation, but PLZ don't make that a habit.

 

There are lots of methods for finding compatible numbers; it depends on the numbers and the operations being performed.  For the given problem, I might ask, "What is 2000 divided by 4?"  Only distractors (b) and (c) are close, but (b) is a good first estimate.

 

Note: when checking answers to other problems, estimating builds confidence that the answer is "in the ball park."