145
Add them up.
The sum of the first 10 odd whole numbers is 100.
The sum of the first five whole numbers is 10.
You know that sum of the first n whole numbers is n(n+1)/2. ( it is the same as the first n natural numbers since the zero does not add anything) So lets say you want the sum of all the whole numbers between 3 and 10. ( I made it easy to illustrate the idea.) The sum of the whole numbers between 0 and 3 is 3(4)/2=6 The sum of the whole numbers between 0 and 10 is 10(11)/2=55 So the sum of the whole numbers between 3 and 10 is the (sum of the whole number between 0 and 10) -(sum of whole numbers between 0 and 3) which is 55-6=49 So in general, for whole numbers m and n with m
6 and 4
9 + 10 + 11 + 12 = 42
9+10+11= 30
At least 9.
There are 17 such numbers.
55
The sum of the first 10 even numbers is 110.
18