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.
Girls may enter puberty at seven, but will experience a majority of their growth in height when they are around 10.5 years old. Boys may begin puberty at the age of eight, but experience growth when they are around 13 years old. Since girls enter puberty before boys, they also experience growth spurts early. This can result in girls towering over boys of the same age. On an average, boys grow the fastest between the ages of 14 and 15.