Count number of numbers between two given numbers?

[saint4life]

For eg, number of numbers from 1-66 = (66-1)+1 = 65
Number of numbers from 2-66 = (66-2) + 1 = 65

(Greater number - Smaller number) + 1?

Is this correct?

[srcc25anu]

Number of numbers between 1 - 66 (both inclusive) = (last - first) +1 or (66-1) +1 = 66
Number of numbers between 2 - 66 (both inclusive) = (last - first) +1 or (66-2) +1 = 65

your formula is correct though. (Greater - Smaller)+1

[800]

But we have to remember the crutial word "inclusive". Some times GMAT play with "exclusive" option. The rule is if there are integers N1 and N2 and if N2 > N1, the number of integers between N1 and N2 , inclusive, is (N2 - N1) + 1.

HTH