874321 is the largest number made from all these digits.
The smallest number is 5,789. The largest is 98,750. The difference is 92,961.
You get the largest number if you sort the digits, from largest to smallest.
the largest five digit number that can be formed using the digits 7 and 9 is 97,000
Number of 7 digit combinations out of the 10 one-digit numbers = 120.
97632 is the largest number containing these digits. To make the largest number simply order the numbers in descending order. As it happens this results in an even number so nothing further is necessary.
The possibilities are all the counting numbers from the largest 16-digit one to the largest 17-digit one.99,999,999,999,999,999 minus 9,999,999,999,999,999 = 90,000,000,000,000,000
For this type of "the largest number which..." questions, you need to advance from left to right, using the largest possible digit in each case. For the first two digits, that would be 9, for the third digit (the right-most digit), the largest digit which will make this possible is an 8.
Pressumably, you want to use each digit once. Starting from the left, use the largest digit you can every time. For example, the left-most digit should be "6".
Using the digits of 1345678, there are 210 three digit numbers in which no digit is repeated.
Proceed from left to right, using the largest possible digit in each position.
That depends a lot on how often you may repeat each digit, and what operations are allowed. If you just want to write a four-digit number, using each digit once, start by writing the largest digit on the left, then continue with the second-largest, etc.
There are 5 numbers which can make the 3 digit numbers in this example. Therefore each digit in the 3 digit number has 5 choices of which number can be placed there. Therefore number of 3 digit numbers = 5 x 5 x 5 = 125