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.
Changes in Boys. Boys tend to show the first physical changes of puberty between the ages of 10 and 16. They tend to grow most quickly between ages 12 and 15. The growth spurt of boys is, on average, about 2 years later than that of girls. By age 16, most boys have stopped growing, but their muscles will continue to develop. Other features of puberty in boys include: The penis and testicles increase in size.