Explanation
To find the sum, we add the numbers together:
11
33
55
77
99
Starting from the rightmost digit (ones place):
1 + 3 + 5 + 7 + 9 = 25
Write down 5 and carry over 2 to the next place.
Moving to the next digit (tens place):
1 + 3 + 5 + 7 + 9 = 25
Add the carry-over 2: 25 + 2 = 27
Combine the digits: 275
So, 11 + 33 + 55 + 77 + 99 = 275