Tropical cyclone scales barometric pressure is low compared with its surroundings. Other classifications historically used include: cyclonic storm where the winds did not exceed force 10 on the Beaufort scale and a Cyclone where the winds are either force 11 and 12 on the Beaufort scale. Between 1924 and 1988, tropical cyclones were classified into four categories: depression, deep depression, cyclonic storms and severe cyclonic storms. However, a change was made during 1988 to introduce the category "severe cyclonic storm with core of hurricane winds" for tropical cyclones, with wind speeds of more than . During 1999 the categories Very Severe Cyclonic Storm
Equate (game) ages 8 and up. The use of fractions stimulates the players interest towards fractions and motives them to want to learn more about fractions. In order to get higher scores, players are constantly taking advantage of premium board positions. Equate uses large numbers. Single digits placed adjacent to one another creates even larger numbers. Equate is also strategically challenging for advanced players who are already good at math. The game adapts to many different levels of play. Advanced Tile Sets take the game of Equate to a higher mathematical level. This particular sets includes 197 tiles with positive and negative