Take the average, which always lies in the middle of any two numbers:
(1413/5689 + 1838/7370) / 2 = 5217548/20963965
To get another number, take the average of this number with any of the first two. For example,
(1413/5689 + 5217548/20963965)/2 = 10424453/41927930
Notice that
1413/5689 ≈ 0.248374
10424453/41927930 ≈ 0.248628 … … … (the second average, between the first number and the first average)
5217548/20963965 ≈ 0.248882 … … … (the first average of the given two numbers)
1838/7370 ≈ 0.249389
(underlined for emphasis)