13 + 23=......................=....................=..........................
13 + 23+33=..........................................=.............=..................
13+ 23+ 33+43=..........................................=..............=........................
13 + 23 = 1 + 8 = 9
13 + 23 + 33 = 1 + 8 + 27 = 36
13 + 23 + 33 + 43 = 100
Tk cho mk nha!!!!!! Ai tk mk thì mk tk lại..
cảm ơn bạn nhiều lắm ^.^