1)16(1-1/2^10)/(1-1/2)
2)1/9(3^8-1)/(3-1)
oh, please. Forget your arithmetic? Lose your calculator? Lose track of google or wolframalpha?
16(1-1/2^10)/(1-1/2)
= 16(1 - 1/1024) / (1/2)
= 32(1023/1024)
= 1023/32
1/9 (3^8-1)/(3-1)
= 1/9 (6560)/2
= 3280/9