(1)0.1+0.2+0.3+0.4+…+0.9+0.1+0.11+0.12+…+0.98+0.99
=(0.1+0.9)×9÷2+(0.1+0.99)×90÷2
=4.5+49.05
=53.55
(2)
+
1 2 1+
1 2
+…+
1 3 (1+
)×(1+1 2
)1 3
1 9 (1+
)×(1+1 2
)×…×(1+1 3
)1 9
=
+
1 2
3 2
+…+
1 3
×3 2
4 3
1 9
×3 2
×…×4 3
10 9
=
+
1 2
3 2
+
1 3
4 2
+…+
1 4
5 2
1 9
10 2
=
+1 3
+1 6
1