The nearest hundred is moving one decimal point up or seeing if the final number is 5 or more. If so, It would round up into 3.23 but its a 3, so the final digit (3) disappears
Multiples of 15 are: 15,30,45,60,75,90,105,120,135,150,165,180,195,210,225,240,255,270,285,300,315,330,345,360,375,390,405,420,435,450,465,480,495,510,525,540,555,570,585,600,615,630,645,660,675,690,705,720,735,
