Question

1/10 + 2/10 + 3/10 + 4/10 + 5/10 + 6/10 + 7/10 + 8/10 + 9/10

tính nhanh

Answer 1

1/10 + 2/10 + 3/10 + 4/10 + 5/10 + 6/10 + 7/10 + 8/10 + 9/10 

= { 1 + 9 } + { 2 + 8 } + { 3 + 7 } + { 4 + 6 } + 5

= 10 + 10 + 10 + 10 + 5

= 45

Answer 2

1/10+2/10+3/10+...+9/10=(1+2+3+4+.....+9)/10=45/10=4,5

Answer 3

=(1+2+3+4+5+6+7+8+9+10)/10=55/10

Answer 4

1/10 + 2/10 + 3/10 + 4/10 + 5/10 + 6/10 + 7/10 + 8/10 + 9/10

\(=\frac{1+2+3+...+9}{10}\)

\(=\frac{\left(9+1\right)+\left(2+8\right)+...+\left(6+4\right)+5}{10}\)

\(=\frac{10+10+...+10+5}{10}\)

\(=\frac{10\times4+5}{10}\)

\(=\frac{45}{10}\)

Answer 5

  1/10 + 2/10 + 3/10 + 4/10 + 5/10 + 6/10 + 7/10 + 8/10 + 9/10

= (1/10 + 9/10) + (2/10 + 8/10) + (3/10 + 7/10) + (4/10 + 6/10) + 5/10

= 1 + 1 + 1 + 1 + 1/2

= 4 + 1/2

= 9/2

Answer 6

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

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

   \(=1+1+1+1+\frac{5}{10}\)

      \(=4+\frac{5}{10}=\frac{9}{2}\)

Answer 7

\(\frac{45}{10}=\frac{9}{2}=4,5\)

vậy ai ra 3 kết quả trên đều đúng

Answer 8

Ta có: 1/10 + 2/10 + 3/10 + 4/10 + 5/10 + 6/10 + 7/10 + 8/10 + 9/10

      =  (1/10 + 9/10) + (2/10+8/10) + (3/10 + 7/10) + (4/10 + 6/10) + 5/10

      = 1 + 1 + 1 + 1 + 1/2

      = 9/2

Answer 9

1/10 + 2/10 + 3/10 + 4/10 + 5/10 + 6/10 + 7/10 + 8/10 + 9/10

=\(\frac{1+2+3+4+...+9}{10}\)

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

=\(\frac{10+10+10+10+5}{10}\)

=\(\frac{45}{10}=\frac{9}{2}\)

Answer 10

\(\frac{1}{10}+\frac{2}{10}+\frac{3}{10}+..............+\frac{9}{10}\)

=\(\frac{1+2+3+.............+9}{10}\)

=\(\frac{45}{10}=\frac{9}{2}=4,5\)

Answer 11

bài này lớp 3 nha các bạn đừng ghi là số thập phân nha _=

Answer 12

1/10+2/10+3/10+4/10+5/10+6/10+7/10+8/10+9/10

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

=1+1+1+\(\frac{5}{10}\)    

=4+\(\frac{5}{10}\)     

=\(\frac{9}{2}\)

Answer 13

45/10

Answer 14

45/10

Answer 15

[1/10+9/10 ]+[2/10+8/10 ]+[3/10+7/10] + [4/10+6/10] +5/10 =9

Answer 16

(1+9) + (2+8)+(3+7)+(4+6)+5

=10+10+10+10+5

=45

Answer 17

1/10 + 2/10 + 3/10 + 4/10 + 5/10 + 6/10 + 7/10 + 8/10 + 9/10

= 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9/10

= 45/10 

Rút gọn = 9/2