First you round 312 to 310 and then you round 287.6 to 290, which equals, 20. ;)
It is 313 because .9 is greater than .5
312
300
312.
312 mm is equal to .312 meters.
312
1,2,3,4,6,8,12,13,24,26,39,52,78,104,156,and 312.
312
312% of 213= 312% * 213= 3.12 * 213= 664.56
312 12*26 = 312 13*24 = 312
It depends on what version you have, but the one I have has 312 pages.