900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 + 900 - 1 = ???????????????????????????????????????????
900 + 900 = ?
100+100+900-900=
199+230=
200+230=?
100+230=?
100+200+300+400+500+600+700+800+900+100+200+300+400+500+600+700+800+900=
LAM HO MK VOI
230 x 981 = ?
230+870+1000