56 if digits can be repeated.
18 if they can't.
Only one . . . 999 .
Only one . . . . . 18
None. The sum of one digit can't be twice the size of the digit.
120
The sum is 154.
There are 5460 five digit numbers with a digit sum of 22.
18 can.
-- If you accept 4-digit numbers with 'zero' as the first digit, thenthere are 24 possibilities, and their sum is 119,988 .-- If the first digit can't be a 'zero', then there are 18 possibilities,and their sum is 115,992 .Note: I didn't repeat any digits.-- If you allow repeated digits, and accept leading zeros, then there are 256 possibilities,and their sum is 1,279,872.-- If you allow repeated digits but not leading zeros, then there are only 192 possibilities,and their sum is 1,247,904.
-3
There are five such numbers.
The largest three-digit number with a digit sum of 10 is 910. This can be determined by maximizing the hundreds place first, setting it to 9, and then adjusting the tens and units places to reach a total digit sum of 10. In this case, using 1 for the tens place and 0 for the units place achieves the desired sum.
The sum of numbers can have as many significant figures as the number with the least significant figures in the original numbers. For example, if you add numbers with 3, 4, and 5 significant figures, the sum will have 3 significant figures.