Categories of Curta Serial Numbers

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Here you can see a full list of Curta serial numbers grouped by category of number. I selected several common categories of positive integer numbers. You can choose one o more categories, also the Curta Type, to see the serial number list of all selected categories. For example, if you want to see all serial numbers of Curtas Type 1 that are Prime number and Palindromic number check Type 1, Prime and Palindromic checkboxes and press Show list.

Of course there are many combinations of categories with no serial numbers, for example, Composite and Prime numbers.

If you want to see the categories of a particular Curta's serial number, please go to Type & Age of your Curta.

This is only for recreational purposes, but please try it and see the results!

Type of Curta:	Type 1	Serial Numbers 901 to 80427
	Type 2	Serial Numbers 500001 to 561660
Category of Numbers:	Composite	It is a positive integer that has at least one positive divisor other than 1 and itself, in other words, it is a non prime number. Read more Curtas of this category: 128809
	Prime	A positive integer that has no positive divisors other than 1 and itself. Read more Curtas of this category: 12378
	Twin Prime	It is a prime number that differs from another prime number by 2, in other words, it is a member of a pair of primes. Read more Curtas of this category: 2882
	Semiprime	It is a positive integer that is the product of two (equal or distinct) prime numbers. Read more Curtas of this category: 31483
	Automorphic	A positive integer whose square "ends" in the same digits as the number itself. For example, 6^2 = 36 (36 ends in 6). Read more Curtas of this category: 1
	Triangular	It is a positive integer that represents the counts of objects that can form an equilateral triangle. The nth triangle number is the number of dots composing a triangle with n dots on a side, and is equal to the sum of the n natural numbers from 1 to n. Read more Curtas of this category: 419
	Square	It is a positive integer that is the square of an integer, in other words, it is the product of some integer with itself. Read more Curtas of this category: 295
	Palindromic	It is a positive integer that remains the same when its digits are reversed. Read more Curtas of this category: 867
	Fibonacci	The Fibonacci numbers (or series or sequence) are the numbers in the following integer sequence: The first two numbers are 0 and 1, and each subsequent number is the sum of the previous two. Read more Curtas of this category: 11
	Perfect	It is a positive integer that is equal to the sum of its proper positive divisors, that is, the sum of its positive divisors excluding the number itself (also known as its "aliquot sum"). Equivalently, a perfect number is a number that is half the sum of all of its positive divisors, including itself. Read more Curtas of this category: 1

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