五年级奥数：竞赛计算题常用解法
在小学数学奥林匹克竞赛中，计算题占有一定的分量，特别是总决赛中还单独设立了计算竞赛（共25
13125+5431+2793+6875+4569
=3125+6875+4569+5431+2793
=22793
2100+99-98-97+96+95-94-93+……+4+3-2
=100+99-98-97+96+95-94-93+92+……+7-6-5+4+3-2
=100+1=101
2+ - - +0960100+3-2
31999998+199998+19998+1998+198+88
=2000000+200000+20000+2000+200+100-2×5-12
=2222300-22=2222278
451.2+48.8+52.5+50.9+47.8+52.3-48.2-59.6
=506-2+1.2-1.2+2.5+0.9-2.2+2.3+1.8-9.6
=200-4.3=195.7
505050
51992×198.9-1991×198.8
=1991×198.9+198.9×1-1991×198.8
=1991198.9-198.8+198.9
=199.1+198.9=398
199119921989198.8198.9=198.8+0.1198.8=198.9-0.1
=+2
a2-b2=a+ba-b
13+23+33+43+……+n3=1+2+3+4……+n2
8100×100-99×99+98×98-97×97+……+2×2-1×1
=100+99100-99+98+9798-97+……+2+12-1
=100+991+98+971+……+2+11
=100+99+98+97+……+2+1
=100+1100÷2=5050
100×100-99×99
3988×4012=40002-122
912+22+32+42+……+102
1153+63+73+83+93
=13+23+33+43+53+……+93-13+23+33+43
=1+2+3+4+5+……+92-1+2+3+42
=452-102=1925
13+23+33+43