以…的倍数
If an amount becomes larger or smaller by a factor of a particular number, it becomes that number of times larger or smaller.
  Cases of leukaemia in the area near the nuclear reactor have risen by a factor of four. 核反应堆附近地区白血病病例已增长4倍。 
 The cost of silver has surpassed the cost of gold by a factor of two in the past year.
 We've managed to cut down production time by a factor of four.
 The rate at which stars are formed varies by a factor of a million between galaxies.
 We could increase the number of doses to 75 million if we dilute the vaccine by a factor of five.
 See also: factor noun (NUMBER)