5050
It's 2550
102*25=2550
5050 To add all numbers from 1 to n: (n/2)(n + 1), in this case n = 100 so it is 50 x 101...
-99
5050
It's 2550
Start at 100 and go on till you reach 999 then stop.
-99
The sum is 2500.
All you do is add all of the numbers 3 times and 1 an 9 4 times
If you can count from 1 to 100, then you can name them all. (And in numerical order, I might add.)
5050, ie (1 + 100) x (100/2)
You can either just add them up or use quick logic to add them in pairs: All the numbers from 1 to 49 match up with 51 through 99 to = 49 pairs of 100 = 4900, than add the two you skipped 4900 + 50 + 100 = 5050 total
-99
102*25=2550
Add them all together then divide the sum by 100 (move the decimal point two places to the left).