1.Tính nhanh
a) 37+397+3997+39997
b) 298+2998+29998+299998
c)9+99+999+9999+99999
2.Tính nhanh
a. (2+4+6+......+2006) - (1+3+5+....+2005)
b.88-87+86-85+....+4-3+2-1
c.100-98 + 96-94 +...+ 8-6 + 4-2
3.Tính nhanh
a.360 -357 +354-351+...+300-297
b. 2006 - 1 -2 -3-4.... - 48-49-50
c.280-276+272 - 268 +...+200 - 196
Giúp mình với nha! Mình đang cần gấp trong hôm nay!Cảm ơn nhiều!Ai trả lời nhanh nhất mình bấm đúng cho nha!
88-87+86-85+....4-3+2-1
giúp mình nhé
2008+2007/2+2006/3+2005/4+2005/5+........................3/2006+2/2007+1/2008
1/2+1/3+1/4+1/5+....................+1/2009
2008+2007/2+2006/3+2005/4+2005/5+........................3/2006+2/2007+1/2008
1/2+1/3+1/4+1/5+....................+1/2009
1 Tính
A (1-1/2) * (1-1/3 ) * (1-1/4 ) * .....*(1-1/19)* ( 1-1/20)
B 3/2 * 4/3 * 6/5* ......* 2006/2005 * 2007/2006 * 2008/2007
1+ 2 - 3 - 4 + 5 + 6 - 7 - 8 + ...... + 2005 + 2006 - 2007 - 2008 + 2009 = ?
A=20008+2007/2+2006/3+2005/4+...+2/2007+1/2008 / 1/2+1/3+1/4+1/5+1/6+1/7+...+1/2008
a=...
1+2-3-4+5+6-7-8+9+10...+2005+2006-2007-2008+2009
1+2-3-4+5+6-7-8+9+10-11-12+...+2005+2006-2007-2008
