Rational numbers are numbers that can be written as a fraction. Irrational numbers cannot be expressed as a fraction.
8
Rational numbers include integers, but they also include fractions.
15 and 16
62 and 63
12 and 13
169 = 144 + 25, so your numbers are 12 & 5.
12 and 13 (and you may note that 12+13 = 25)
5 and 6
2 and 5 are the only prime numbers which differ by 3.
Every tow consecutive odd or even numbers differ by two.
72 and 40