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.
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.
9876 is the largest four digit number you can make if all the digits must be different.
9999
Using a calculator will make it easier
what is the largest 4-digit number you can make
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.
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.
9876 is the largest four digit number you can make if all the digits must be different.
543,210. If you can use them all multiple times, then it is 555,555.
999next number is 1,000
9999
9,999
Using a calculator will make it easier
9,864,320
99996
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.