1+2+3+4+5+6+7+8+9=45
nhớ k cho mình nha
1+2+3+4+5+6+7+8+9
=(1+9) + (2+8) + (3+7) + (4+6) +5
=10 + 10 + 10 + 10 +5
=45
kq la45
nho k cho minh nhe ai k cho minh minh k lai cho
bang 45 nhe ban
ai h cho minh minh h lai cho
1+2+3+4+5+6+7+8+9
=3+3+4+5+6+7+8+9
=6+4+5+6+7+8+9
=10+5+6+7+8+9
=15+6+7+8+9
=21+7+8+9
=28+8+9
=36+9
=45
=(1+9)+(2+8)+(3+7)+(4+6)+5
= 10 + 10 + 10 + 10 +5
= 45