1 + 5 + 9 + 13 + ....... + 57 + 61 + 65
A=12.194+6.437.2+3.369.4 trên 1+5+9+13....+57+61+65-2-26
12 . 194 + 6 . 437 . 2 + 3 . 369 . 4
1 + 5 + 9 + 13 + .............. + 57 + 61 + 65 .2 - 26
tính nhanh
12.6437 .2+3.369.4
-------------------------------------------------
1+5+9+13+...+57+61+652-26
a) 12.194+6.437.2+3.3.369.4tren 1+5+9+13+........+57+61+65.2-26
A=12.194+6.437.2+3.369.4
1+5+9+13+...+57+61+65.2-26
tính nhanh
1+3-5-7+9+11-13-15+17+...-57-59+61+63
A = 12 . 194 +6 . 437 . 2 +3 . 369 .4
B = 1 + 5 +9 + 13 +.............. + 57 + 61 +124 - 26
Tính A/B
1)12.194+6.437.2+3,369.4
2)1+5+9+13+........+57+61+65.2-26
3)8.9.14+6.17.12+19.4.18
4)1+2-3-4-5+6-7-8+9+994-995-996+997+998
5)1994.19931993-1993.19941994