What is pi, and how did it originate? Succinctly, pi--which is written as the Greek letter for p, or --is the ratio of the circumference of any circle to the diameter of that circle. Regardless of the circle's size, this ratio will always equal pi. In decimal form, the value of pi is approximately 3.14.
Inverted repeat. An inverted repeat (or IR) is a single stranded sequence of nucleotides followed downstream by its reverse complement. The intervening sequence of nucleotides between the initial sequence and the reverse complement can be any length including zero. When the intervening length is zero, the composite sequence is a palindromic sequence.
Top 10 Palindromes. Palindromes are the most symmetrical words and phrases youâll ever encounter. Also, the most amusing, when you think of the nonsense and ambiguous meanings that can come from trying to achieve perfect syntactical harmony. Here are ten for those who like to read things front to back (and then back to front again).