The four most common number system types are:

The number system of the English language is of this type (“three hundred [and] four”), as are those of other spoken languages, regardless of what written systems they have adopted.

Our base ten number system is called the Hindu-Arabic system. In this system there are ten different symbols (digits) to represent quantities, 0,1,2,3,4,5,6,7,8,9.

Decimal system, also called Hindu-Arabic number system or Arabic number system, in mathematics, positional numeral system employing 10 as the base and requiring 10 different numerals, the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. …

The most commonly used numeral system is the decimal positional numeral system, the decimal referring to the use of 10 symbols—0, 1, 2, 3, 4, 5, 6, 7, 8, 9—to construct all numbers.

• Binary number system (Base-2)
• Decimal number system (Base- 10)
• Octal number system (Base-8)
• Hexadecimal number system (Base- 16)

“COMPLEX NUMBER” IS THE BIGGEST NUMBER SET IN NUMBER SYSTEM BECAUSE ITS CONTAIN ALL REALL VALUE AND IMAGINARY VALUE.

Twin primes are pairs of prime numbers of the form (p, p+2), for example (3, 5), (5, 7), (11, 13). The first 25 prime numbers (all the primes less than 100) are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

The first fifteen pairs of twin primes are as follows: (3, 5), (5, 7), (11, 13), (17, 19), (29, 31), (41, 43), (59, 61), (71, 73), (101, 103), (107, 109), (137, 139), … Also check: Prime Factors.

So, all the pairs of twin primes between 50 and 100 are – (59,61) and (71,73)