There are 20 odd numbers in 40.
The sum of the first 40 odd numbers is 1,600.
The odd numbers between 40 and 53 are 41,43,45,47,49,51.
There are 40 odd numbers between 20 and 100. Remember that an odd number is every second number. There are 80 numbers between 20 and 100, so there are 40 odd numbers and 40 even numbers.
You can't. Adding any two odd numbers always gives an even number, which is not a member of the set of odd numbers.
45
How many odd numbers are there from 16 to 30? Seven {7} odd numbers
These numbers between 1 and 40 have an odd number of factors: 4, 9, 16, 25, 36.
The odd numbers between 30 and 40 are: 31 33 35 37 39
30
7
11