Introduction to Number Theory

In number theory, the numbers are classified into different types, such as natural numbers, whole numbers, complex numbers, and so on. The sub-classifications of the natural number are given below:

• Odd Numbers – 1, 3, 5, 7, 9, 11, 13, 15, 17, 19…..
• Even Numbers – 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22 . . .
• Square Numbers – 4, 9, 16, 25, 36, 49, 64, 81,100 . . .
• Cube Numbers – 8, 27, 64, 125, 216, 343, 512 . . .
• Prime Numbers – 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47,53, 59, 61 . . .
• Composite Numbers – 4, 6, 8, 9, 10, 12, 14, 15, 16,18, 20, 21, 22, 24 . . .
• 1 (modulo 4) Numbers – 1, 5, 9, 13, 17, 21, 25, . . .
• 3 (modulo 4) Numbers – 3, 7, 11, 15, 19, 23, 27, . . .
• Triangular Numbers – 3, 6, 10, 15, 21, 28, 36, 45,. . .
• Perfect Numbers – 6, 28, 496, 8128, . . .
• Fibonacci Numbers -1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. . .

Many of these types of numbers like odd, even, square, cube prime and composite numbers are already familiar to you. Other cases, such as the “modulo 4” numbers, Triangular numbers, perfect numbers and Fibonacci numbers are not familiar to you.