小学二年级奥数题及答案:巧算问题
1.巧算问题
计算:19+19+29+29=
解答:原式
=20+20+30+30-1-1-1-1
=40+60-4
=100-4
=96
2.巧算问题
38+37-36-35+34+33-32-31+30+29-28-27+26
2+4+6+8+10+12+14+16+18+20=
=(38+37-36-35)+(34+33-32-31)+(30+29-28-27)+26
=4+4+4+26
=8+30
=38