10 + 20 + 3 + 40 + 50 + 60 + 70 + 80 + 90 = 423
k mk nha
công chúa mặt trăng
10+20+3+40+50+60+70+80+90
=(10+90)+(20+80)+(40+60)+(50+70)+3
=100+100+100+120+3
=420+3
=423
k mình nha
10 + 20 + 3 + 40 + 50 + 60 + 70 + 80 + 90 = 423
k mk nha công chúa mặt trăng
\(10+20+30+40+50+60+70+80+90\)
\(=\left(10+90\right)+\left(20+80\right)+\left(40+60\right)+50+3+70\)
\(=100+100+100+50+3+70\)
\(=100.3+50+3+70\)
\(=300+50+3+70\)
\(=350+3+70\)
\(=353+70\)
\(=423\)
