Question

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

Answer 1

A=1+2+3+.........+10

=(1+10)+(2+9)+...........+(5+6)

=11+11+11+11+11

=11 x 5

=55

Answer 2

2A=11x20:2

2A=110:2

A=55

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Answer 3

bằng 45

Answer 4

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

= 10 + 10 + 10 + 10 + 10 + 5

= 10 * 5 + 5

= 50 + 5 

= 55

Answer 5

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

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

= 10 + 10 + 10 + 10 + 10 + 5

= 10 * 5 + 5

= 50 + 5 

= 55

Answer 6

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

A = 10 x ( 10 + 1) : 2

A = 10 x 11 : 2

A = 110 : 2

A = 55

Answer 7

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

A=11*5

A=55

Answer 8

\(A=1+2+3+4+5+6+7+8+9+10=\frac{\left(10+1\right)}{2}\times\left(\frac{10-1}{1}+1\right)=55\)

Answer 9

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

= 10 + 10 + 10 + 10 + 10 + 5

= 10 * 5 + 5

= 50 + 5

= 55

Answer 10

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

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

A =     11       +     11    +     11     +      11    +      11

A =                                 11 x 5

A =                                    55