(1)½+¾+7/8+15/16+31/32+63/64
=(1-½)+(1-1/4)+(1-1/8)+(1-1/16)+(1-1/32)+(1-1/64)
=6-(½+1/4+1/8+1/16+1/32+1/64)
=6-(1-1/64)
6-63/64
=321/64
(2)1+1/3-7/12+9/20-11/30+13/42-15/56
=1+1/3-(1/3+1/4)+1/4+1/5-(1/5+1/6)+1/6+1/7-(1/7+1/8)
=1-1/8
=7/8
(3)2/3+2/15+2/35+2/63+2/99
=1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11
=1-1/11
=10/11
(4)3/2+7/3-13/4+25/6
=(1+2-3+4)+(1/2+1/3+1/6)-1/4
=4+1-1/4
=19/4
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