What is the greatest four digit number formed using the digits 5, 3, 9 and 1. Estimate the number to the nearest tens.

A. 9350
B. 9540
C. 9510
D. 9530

Answer: D

The greatest digit would be 9, followed by 5, then 3, and finally 1.

So, the greatest four-digit number using these digits is 9531.

Now, let’s estimate this number to the nearest tens. Since the ones place digit is 1, which is less than 5, the tens place remains unchanged as 30, and the ones place becomes 0.

The estimated greatest four-digit number to the nearest tens is 9530.