(1)1-3+5-7+9-11+.....+97-99 (共50个奇数岁闷)
=-2-2-2-.....-2 (共25个-2)
=-2×25=-50
(2) 501+502+.....+600
=500×100+(1+2+3+.....+100)
=50000+(1+100)×100/孙雀搏2 (此步可省则祥略)
=50000+5050
=55050
1)=(1-3)神谨指+(5-7).......+(游配97-99)
=-2*33
=-66
2)=(501+600)*100/晌好2
=1101*50
=55050
1、…=(1-3)野袭+(5-7)+……+(97-99)
=-2*25=-50
2、…乱郑=(501+600)颂陪兄*100/2=55050