1)  (27-514)-(486-78)

    =-487-408

   =-895

2)=40

3)=407

1. \(\left(27-514\right)-\left(486-78\right)\)

\(=\left(-487\right)-408\)

\(=-895\)

2. \(\left(65-100\right)-\left(25-100\right)\)

\(=\left(-35\right)-\left(-75\right)\)

\(=40\)

3. \(\left(567-67\right)-\left(56+4+33\right)\)

\(=500-93\)

\(=407\)

\(Cau1\left(27-514\right)-\left(486-78\right)\)

\(=\left(-487\right)-408\)

\(=-895\)

\(Cau2:\left(65-100\right)-\left(25-100\right)\)

\(=-35-\left(-75\right)\)

\(=40\)

\(Cau3:\left(567-67\right)-\left(56+4+33\right)\)

\(=500-\left(60+33\right)\)

\(=500-93\)

\(=407\)

a) 31 . 65 + 31 . 35 - 500

=31(65+35)-500

=31..100-500

=3100-500

=2600

a, 31.56+31.35-500

=31(65+35)-500

=3100-500

=2600

 253 - (-76 + 253) + 99 =175

68 - (199 + 68) - (-150) = -49

211 - (107 + 211) - 23 = -130

-(-345 + 56 - 267) + (453 - 124 - 843) =42

-25 - (34 - 256 + 67) - (-2) + (-10 - 65) =57.

cứu

a) 10; 13; 18; 26; 36; 52...

c) 0; 1; 4; 9; 16; 25...

m) 1; 4; 9; 16; 25; 36; 49; 64...

p) 1; 3; 9; 27; 81; 243...

Anh ko để ý lên hạng nhanh j

25 + 65 – 30 = 90 – 30 = 60.

90 – 40 – 26 = 50 – 26 = 24.

a)  

\(\dfrac{1}{2}=0,5;\dfrac{3}{4}=0,75;\dfrac{7}{5}=1,4;\dfrac{9}{8}=1,125;\dfrac{26}{25}=1,04;\dfrac{120}{125}=0,96\)

b) 

\(\dfrac{15}{25}=0,6;\dfrac{75}{25}=3;\dfrac{90}{300}=0,3;\dfrac{27}{36}=0,75;\dfrac{51}{85}=0,6\)

a,1/2=5/10;3/4=75/100;7/5=140/100;26/25=108/100;120/125=960/1000

b,15/25=60/100;75/25=300/100;90/300=3/10;27/36=3/4=75/100;

51/85=3/5=60/100;39/65=3/5=60/100

Bài 1:

a: 212+109+188

=212+188+109

=400+109

=509

b: 305+295+140

=600+140

=740

c: \(9\cdot4\cdot25\cdot8\cdot125\)

\(=9\cdot100\cdot1000\)

=900000

d: 35+56+65+44

=35+65+56+44

=100+100

=200

e: 277+194+206+123

=277+123+194+206

=400+400

=800

g: \(8\cdot25\cdot2\cdot4\cdot5\cdot125\)

\(=2\cdot5\cdot4\cdot25\cdot8\cdot125\)

\(=10\cdot100\cdot1000=1000000\)

h: \(29\cdot25+29\cdot45+29\cdot30\)

\(=29\left(25+45+30\right)=29\cdot100=2900\)

i: \(36\left(143+57\right)+64\left(143+57\right)\)

\(=36\cdot200+64\cdot200\)

\(=200\left(36+64\right)=200\cdot100=20000\)

k: \(491\cdot\left(747+53\right)+491\left(153+47\right)\)

\(=491\left(747+153+53+47\right)\)

\(=491\left(900+100\right)=491\cdot1000=491000\)

Bài 4:

a: M=1+2+3+...+103

\(=\frac{103\left(103+1\right)}{2}=103\cdot\frac{104}{2}=103\cdot52=5356\)

b: Số số hạng của dãy là (99-3):4+1=96:4+1=24+1=25(số)

Tổng của dãy số là:

\(N=\left(99+3\right)\cdot\frac{25}{2}=51\cdot25=1275\)

c: Số số hạng của dãy là:

(991-1):10+1=990:10+1=99+1=100(số)

Tổng của dãy số là:

\(C=\left(991+1\right)\cdot\frac{100}{2}=992\cdot50=49600\)