Question

In how many ways can the digits 2,3,5,7 and 9 be placed to form a three-digit number so that the higher order digit is always greater than the lower order digits? (assume digits are all different).

Answer 1

Answer:

10 ways

Step-by-step explanation:

Detailed explanation of the question by giving one of the correct answer:

975

9 is higher than the next number 7.

7 is higher than the next number 5

Combinations:

3 digits starting with 9. Here you can combine 7, 5, 3, and 2.

975, 973, 972

953, 952,

932

Then 3 digits starting with 7, you can combine 5, 3 , and 2

753, 752

732

Then lastly, 3 digits starting with 5, you can combine 3 and 2

532

You cannot further use 3 and 2 since you cannot form any 3 digit number as they are lower than 5, 7, and 9.