Jessie adds ten numbers. Each number has three digits. What is the greatest possible number of digits in the sum? Explain?

There are 10 numbers

Each of these numbers is a 3-digit number

There is no restriction on the digits of a particular number to be unique

We have to find out the greatest possible number of digits in the sum of these 10 numbers

To find the greatest possible number of digits, let's assume that all of the numbers are the greatest possible 3-digit number i. e. all numbers are 999.

sum of 10 numbers = 999 + 999 + 999 + 999 + 999 + 999 + 999 + 999 + 999 + 999

⇒ sum of 10 numbers = 999 * 10

⇒ sum of 10 numbers = 9990

So the number of digits in 9990 is 4. Since, this is the highest possible sum, the number of digits can never exceed 4 for sum of 10 3-digit numbers.