Question

简便计算 急。。。谢谢

28+19-49-997+9996 1/2+1/4+1/8+1/16+1/32+1/64

Answer 1

28+19-49-997+9996
=30+20-50-1000+10000-2-1+1+3-4
=9000-3
=8997
28+19-49-997+9996
=28+19-50+(9997-997)
=9000+30+20-50-3
=9000-3
=8997

1/2 + 1/4+1/8+1/16+1/32+1/64
＝(64-1)/64
＝63/64

Answer 2

1.28+19-49-997+9996
=(30-2)+(20-1)-(50-1)-(1000-3)+(10000-4)
=30-2+20-1-50+1-1000+3+10000-4
=(30+20-50)+(10000-1000)+(3-2-1)+(1-4)
=9000-3
=8997
或28+19-49-997+9996
=(30-2)+(20-1)-49-997+(9997-1)
=30-2+20-1-49-997+9997-1
=(30+20-49-1)+(9997-997)-(2+1)
=9000-3
=8997
2.1/2+1/4+1/8+1/16+1/32+1/64
=(1-1/2)+(1/2-1/4)+(1/4-1/8)+(1/8-1/16)+(1/16-1/32)+(1/32-1/64)
=1-1/2+1/2-1/4+1/4-1/8+1/8-1/16+1/16-1/32+1/32-1/64
=1-1/64
=63/64