（1）分母为99的最简分数有多少个（2）60占它全部应数之和的几分之几（3）分数单位为90的所有真分数之和是

Question

如题所述

Answer 1

（1）分母为99的最简分数有多少个
1/99,2/99, 4/99, 5/99, 7/99, 8/99, 10/99, 13 /99, 14/99. 16/99, 17/99, 19/99, 20/99, 23/99, 25/99, 26/99, 28/99, 29/99, 31/99, 32/99,, 34/99, 35/99,37/99, 38/99, 40/99, 41/99, 43/99, 46/99, 47/99,49/99,50/99,52/99,53/99,56/99 ,58/99,59/99,61/99,62/99,64/99,65/99,67/99,68/99,70/99,71/99,73/99,74/99,76/99,79/99,80/99,82/99,83/99,85/99,86/99,89/99,91/99,92/99,94/99,95/99,97/99,98/99.

（2）60占它全部应数之和的几分之几
(1+2+3+4+5+6+10+12+15+20+30+60)÷60=168/60

（3）分数单位为90的所有真分数之和是
1/90+7/90+11/90+13/90+17/90+19/90+23/90+29/90+31/90+37/90+41/90+43/90+47/90+53/90+59/90+61/90+67/90+71/90+73/90+77/90+79/90+83/90+89/90+91/90+97/90
=1219/90