Quant Arithmetic - Number of integers & pairs problem

GRE Quant Problem Solving
1

Hi, I am new to Gregmat.

I have some questions on how to determine the number of integers & pairs from an evenly spaced interval, and from 50 to 303. The questions are given below.

We know that, formula for Total Number of Integers in an interval (inclusive),
n = Last Number − First Number + 1.
And formula for Total Number of Pairs in an interval = (n/2) if last number in the interval is even
= (n-1)/2 if last number in the interval is odd

  1. Can I use the same formula for an evenly spaced interval like (22, 24, 26, 28,…,1026) inclusive to determine the number of integers in this interval?
  2. What formula should I use for determining Total Number of Pairs in (22, 24, 26, 28,…,1026) interval?
  3. If total number of integers from 50 to 300, inclusive is (300 - 50 +1) n = 251 and total number of pairs = n/2 = 251/2 = 125.5, total number of integers from 50 to 303, inclusive will be (303 - 50 + 1) n = 254 and total number of pairs = (254 - 1)/2 = 126.5 (since 303 is odd, I use (n-1)/2 formula). Is my math correct?
2

Have you covered Number of MULTIPLES in an interval yet in your study plan?

22, 24, 26, 28,…,1026

You could rephrase this as: How many multiples of 2 between 22 and 1026, right?

3

Thanks for the reply. No, I have not covered the number of multiples topic yet. Will I get the theories and clues for my questions to 1 and 2 there? Is my math correct in 3?