giup mk vs
1 Tinh nhanh
a, 17+18+19+...+99
b, 23+25+27+..+49
c,46-45+44-43+..+2-1
d, 5+8+11+14+...+38+41
e, 49-51+53-55+57-59+61-63+65
2 tinh tong cua
a, tat ca cac stn co 3 cso
b, tat ca cac stn co 4 cso
c,tat ca cac stn le co 3 cso
d, tat ca cac stn le co 4cso
e, tat ca cac stn day:2,5,8,..., 296
f, tat ca cac stn day: 7,11,15,19,...,283
Không khó ! Nhưng ngán làm !!!