Answer: Because 9999 is the largest four-digit number, a maximum value may be created by adding 9999 and 9999, and the resulting number will have **the greatest number** of digits. In this case, the answer is 180000000.

- What is the maximum sum of digits for a 4-digit number?
- What is the smallest and greatest 4-digit number?
- What is the smallest positive 4 digit number?
- What is the largest number you can write by using only 3 digits and it’s not 999?
- What is the sum of the greatest four-digit numbers?
- What is the largest 4-digit positive integer?
- How many four-digit positive integers are there?
- How many digits is 1000?

1000 is the lowest four-digit number, while 9999 is the largest four-digit number. This is because each digit can be assigned a value from 0 to 9, and there are 10 possibilities for each position. A four-digit number can have up to four items equal to 9, and still be valid.

Four-digit numbers can be divided into groups of three digits that add up to nine. These are called triads. For example, the number 456 is composed of three triads: 44 + 56 = 100, which is equivalent to 3+0+4 = 7. The total number of triads in 456 is 3 × 7 = 21. Numbers that contain **the same number** of triads but in a different order are considered to be the same number. For example, 456 and 654 are the same number because they contain the same number of triads in a different order. There are only ten different ways to arrange these triads; thus, there are only ten four-digit numbers that contain exactly three 9's.

A number is called perfect if it is equal to the sum of **its parts** or, in other words, if each of its digits is equal to the sum of its own value plus two times the value of the previous digit.

1,000 The lowest 4-digit number is 1,000, and the biggest 4-digit number is 9,999, for a total of 9000 numbers ranging from 1000 to 9999. We may generate **numerous four-digit numbers** by employing digits ranging from 0 to 9, but keep in mind that the thousand place in **a four-digit number** should never be 0. For example, the number 4000 is not valid because it would be interpreted as 40,000.

An alternative way of looking at **this problem** is to ask, "What is the least possible number that can be written using only the digits 0 through 9?" The answer is 10, which can be seen by counting the number of times each digit appears in the decimal system: 1 followed by 0 or more zeros. Therefore, the smallest positive integer that can be written using only these digits is 10,000.

Another method would be to take the first step of multiplying all the factors from 1 to 9, then adding them together. This gives us a final answer of 10,000. Although this seems like a lot of work, it can be done quickly on a computer. There are also apps available in the Android Market and iTunes App Store that will help you calculate this number for you.

10,000 was originally patented by George Bell in 1869. He called it a "method and means for calculating the value of interest on mortgages."

Interest on loans comes in **two forms**: simple interest and compound interest.

The following are the largest numbers that may be constructed using three digits: If all three numbers may be repeated, the needed number is 999. If just two numbers may be repeated, the answer is 998. The number is 987 if no repeat is permitted. Thus, the largest number you can write using **only these three digits** is 999.

The highest four-digit number is 9999. 1000 + 1 Equals 1001 (one more than **the lowest four-digit number**). As a result, the sum of **the largest four-digit number** and one more than the lowest four-digit number is 11,000.

This problem can also be solved by adding **all nine digits** and dividing by 10. The answer is obtained by multiplying the number by 100 and removing **the last two zeros** before entering it into a computer or calculator. This process is known as rounding off.

Note that there are different methods to solve this problem. You can use your knowledge of mathematics to solve it quickly, for example by considering that the largest four-digit number must be greater than 999 and less than 10000. It can be shown that 11111 = 79991 which is close to 11000 so this might be a good start.

You could also write a program to calculate it. In fact, there are many online calculators that will do this for you.

The difference between **the smallest 4-digit positive integer**, 1000, and the greatest 3-digit positive integer, 999, is one. If negative integers are permitted, the smallest four-digit integer is-9999 and the highest three-digit integer is 999; 9999 = 999 = -10998. There are no four-digit positive integers except 0 and 1000.

The first 999 numbers have three or less digits, while the last four-digit number is 9999. As a result, 9000 is the sum of the numbers with up to four digits minus the ones with three or less digits. For these reasons, it is often called the "million-dollar number" or the "ten-million-dollar number."

It's easy to see that there are 1000 numbers with up to four digits: 0, 1, 2, 3,... 998, 999. But what about **the other two digits**? They can be any digit except 9, so there are 10 choices for each digit. Thus, there are 10*998=9,980 numbers with up to four digits.

Now we need to subtract the numbers with **three or fewer digits**. There are only nine numbers with **two digits**: 22, 33, 44, 55, 66, 77, 88, 99. We can divide the rest of the numbers by 100 to find out how many numbers there are with **one digit**: 101, 202, 303, 404, 505, 606, 707.. 9999. This number is equal to 99999/100 which equals 100000.

So in total, there are 9,980 + 100,000 = 109,980 numbers between 0 and 49999.

1000 is made up of four digits. It is divided by 10 to find out how many times it should be multiplied by 10 to get 1000.

So, 1000 = 4 * 250. 250 is the first digit, so we move on to the next column. 1,000 - 250 = 750. The third digit is then placed in the cell below the first one (since they are both counting numbers). This leaves us with the last column which contains only ones. So, we multiply 750 by 10 and come up with 7500 as the answer.

1000 has been done already. It takes 4 times 10 to get 40,000. Keep in mind that once you enter a number into a cell, it remains there until you change it. So, if you wanted to work out **another number** from 1000, you would simply divide the original number by 10 and write down the new number in the same cell as the first one. For example, if you were working with 990, you would divide 100 by 10 (or round down) to get 9. 90 ÷ 10 = 9, so now you have two numbers: 990 and 1000.