Question

The greatest number formed by 9, 8 and 7 is
$
  (a){\text{ 987}} \\
  (b){\text{ 789}} \\
  (c){\text{ 897}} \\
  (d){\text{ None of the above}} \\
 $

Answer 1

Hint: The greatest number using 9, 8 and 7 can only be formed using the highest digit among them which is 9 as the first digit of the number. Then we have to decide which will be the second digit of the remaining two digits, so it has to be the highest of the remaining digits.

Complete step-by-step answer:
Given digits are 9, 8 and 7.
Now we have to find out the greatest number using these digits only.
Greatest number – The greatest number is always starting from the highest number amongst the given digits followed by least digits.
So amongst the given digits the highest digit is 9 so first place is filled by 9.
Now the second place is filled by the second highest digit which is 8.
And the third place is filled by the least digit (as there are only three digits) which is 7.
So the greatest number formed is 987.
So 987 is the greatest number formed by digits 9, 8 and 7.
Hence option (A) is correct.

Note: Whenever we face such types of problems the key concept is simply to understand that the greatness of a number based upon the magnitude is always measured using its right most digit which may be on the hundredth place or less. This concept will help to get on the right track to reach the answer.