The first, smallest, and only odd prime gap is 1 between the only even prime number, 2, and the first odd prime, 3. All other prime gaps are even. There is only one pair of gaps between three consecutive odd natural numbers for which all are prime. These gaps are g2 and g3 between the primes 3, 5, and 7.
Girls usually start their periods between the ages of 10 and 16. Most girls start when they're around 12. As everyone develops at different rates, there's no right or wrong age for a girl to start. Your periods will start when your body is ready, and there's nothing you can do to make them start sooner or later. If you haven't started your periods by the time you're 16, visit your doctor for a check-up.
Q:Girls should have their periods by the time they are 13. Q:Girls should have their periods by the time they are 13. Everyone develops at their own rate. A doctor should be consulted for girls who have not gotten their periods by age 15 or within a few years of breast growth. It is important to note that some girls don't get their periods until they're 16. Often the best predictor of when a girl will get her first period is when her mother got her first period.