1 + 2 + 3 + 4 + 5 + 6 + 7 + 89 + 10
= (1 + 89) + 2 + (3 + 7) + (4 + 6) + 5 + 10
= 90 + 2 + 10 + 10 + 5 + 10
= 120 + 2 + 5
= 127
1 + 2 + 3 + 4 + 5 + 6 + 7 + 89 + 10
= (1 + 89) + (3 + 7) + (4 + 6) + (2 + 5) + 10
= 90 + 10 + 10 + 7 + 10
= 10. 12 + 7
= 120 + 7
= 127
1+2+3+4+5+6+7+89+10
(1+89)+(3+7)+(4+6)+2+5+10
90+10+10+2+5+10
127