= (1+9) +(2+8) +(3+7) + (4+6) + (5+11)
= 10 + 10 +10 +10 +21
=61
=(9+1)+(8+2)+(7+3)+(6+4)+10+5+11
=10+10+10+10+10+15
=50+15
=65
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11
= ( 1+11) +( 2 + 10) + (3+9) + (4 + 8) + (5 + 7) + 6
= 12 + 12 + 12 + 12 + 12 + 6
= 12 x 5 + 6
= 60 + 6
= 66
1+2+3+4+5+6+7+8+9+10+11
=( 11+1)+(10+2)+(9+3)+(8+4)+(7+5)
=12+12+12+12+12
=12x5
=60
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11
= (1 + 11) x 11 : 2
= 12 x 11 : 2
= 132 : 2
= 66 nha!
1+2+3+4+5+6+7+8+9+10+11
=(11+1)+(10+2)+(9+3)+(8+4)+(7+5)+6
=12+12+12+12+12+6
=12x5+6
=60+6
=66
1+2+3+4+5+6+7+8+9+10+11
=(11+1)+(10+2)+(9+3)+(8+4)+(7+5)+6
=12+12+12+12+12+6
=12x5+6
=60+6
=66