110+210+310+410+510+610+710+810+910+5510=

1+ 2+ 3 + 4 + 5 + 6 + 7 + 8 + 9 = (9)(10)2 = 45 45+5510 = 10010 = 10

jmc

prealgebra junior

Problem

\frac{1}{10} + \frac{2}{10} + \frac{3}{10} + \frac{4}{10} + \frac{5}{10} + \frac{6}{10} + \frac{7}{10} + \frac{8}{10} + \frac{9}{10} + \frac{55}{10} =

(A)

4 \frac{1}{2}

(B)

6.4

(C)

9

(D)

10

Solution

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = \frac{( 9 ) ( 10 )}{2} = 45

\frac{45 + 55}{10} = \frac{100}{10} = 10

Final answer