Giải thích các bước giải:
`2 1/4+1/8+1/16+1/32+1/64+1/128`
`=2+1/4+1/8+1/16+1/32+1/64+1/128`
Đặt `A=1/4+1/8+1/16+1/32+1/64+1/128`
`=>2A=1/2+1/4+1/8+1/16+1/32+1/64`
`=>2A-A=(1/2+1/4+1/8+1/16+1/32+1/64)-(1/4+1/8+1/16+1/32+1/64+1/128)`
`=>A=1/2-1/128`
`=>A=63/128`
`=>2 1/4+1/8+1/16+1/32+1/64+1/128=2+63/128=2 63/128.`