It is in the middle: (123+309)/2 = 216
The sum of 123 is 123.
216.
It is: 216+248 = 464
7272 * * * * * WRONG! Sum from 23 to 123 = (sum from 1 to 123) minus (sum from 1 to 22) = 123*124/2 - 22*23/2 = 7626 - 253 = 7373. NOT 7272!
217
The sum of 123 and 2,223,223 is 2,223,346
It is: 190+119 = 309
71 + 72 + 73 = 216
The sum of 123 and 654 is 777.
113+7+3 = 123
123
512