(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9) - 55
= (10 + 10 + 10 + 10 + 5) - 55
= 45 - 55
= -10
(1+2+3+4+5+6+7+8+9)-55
=45-55
=45+(-55)
=-10
nha 
(1+2+3+4+5+6+7+8+9)-55
=(1+9)x9:2-55
=10x9:2-55
=90:2-55
=45-55
=-10
(1+2+3+4+5+6+7+8+9)-55
=(1+9)+(2+8)+(3+7)+(4+6)+5-55
=10+10+10+10+5-55
=40+5-55
=45-55
=-10
(1+2+3+4+5+6+7+8+9)-55 =(1+9)+(2+8)+(3+7)+(4+6)+ 5 -55 = (10 + 10 + 10 + 10 +5) -55 = ( 10 x 4 + 5 ) - 55 = 45 - 55 = -10
tìm x
1) [(3/8.x-1/2):5/7+4/9].6/11=18/55
2) (7/10-3.x):( 1 9/10-1 2/5)+4/5=1
1+1+1+1+2+2+2+3+3+3+3+4+4+4+4+5+5+5+5+6+6+6+6+7+7+7+7+8+8+8+8+9+9+9+9+10=
8/9÷3/7=
8/9+2/5=
7/8-1/3=
3/10×1/6=
b.hỗn số
1 2/7+6 5/6=
5 3/4-1/5 =
6 2/9÷4 7/10=
5/3+3/2-7/6=
1+2+3+4+5+6++7+8+9+9+8+7+6+5+4+3+2+1+1+2+3+4+5++6+7+8+9=?
Tính nhanh
A=1×5×6+2×10×12+24×8×10/1×35+2×6×10+8×6×20
B=2006×2008-3/2005+2005×2008
C=18×123+9×4567×2+3×5310×6/1+4+7+.......+55+58-410
1+2+3+4+5+6+7+8+9+1+2+3+4+5+6+7+8+9+1+2+3+4+5+6+7+8+9 +1028 giúp mk nha
1+2+3+4+5+6+7+8...........+1000:55=?
Sap xep cac phan so sau theo thu tu tu lon den be
8/9; 4/5; 9/8; 3/4; 10/9; 12/12; 7/8; 1/6; 1/4; 3/2; 1/5; 8/7; 6/5; 5/6; 4/3; 6/7; 2/3; 2/15; 1/2;5/4
