The abacus is believed to have been developed in the ancient Near East in the third millennium BCE. An abacus consists of a series of thin parallel bars set into a rectangular frame, usually made of wood. Each bar contains a number of beads that slide along its length. Individuals use the beads as number counters and use the abacus to perform addition, subtraction, multiplication, and division.
How to Hit Puberty Faster. Puberty is that time of life when a childâs body matures into the body of an adult. Puberty for boys starts usually between the ages of 9 and 14 years old. The symptoms of puberty in boys include enlargement of testicles and penis, growth of underarm hair, facial and pubic hair, deepening of voices and a growth spurt.
WebMD News Archive. Oct. 20, 2012 -- American boys are starting puberty up to two years earlier than decades ago, new data show. Boys are entering puberty at an average age of 10 among whites and Hispanics, and at an average age of 9 among African-Americans. About a third of boys start to mature sexually up to two years earlier than average. The findings come from a study of 4,131 boys examined at doctors' offices across the U.S. by Marcia Herman-Giddens, DrPH, and colleagues. The same team found a year-earlier shift in first puberty for girls.