126 + 162 + 216 + 261 + 612 + 621 = 1998

ko thuận tiện đc

công như sau :

126 + 162 + 612 = 900

216 + 261 + 621 = 1098

cộng :

900 + 1098 = 1998

đ/s : 1998

nhé !

126+162+216+261+612+621

=(126+162)+(216+261)+(612+621)

=288+477+1233

=1998

k mình nhé

bằng 3998

35*64+162*162+162

=35*64+162*162+162*1

=35*64+162*(162+1)

=35*64+162*163

=2240+26406

=28646

36 x 5 + 72 x 2 - 216 + 144

= 252

\(36\text{×}5+72\text{×}2-216+144\)

\(=36\text{×}5+36\text{×}2\text{×}2-36\text{×}6+36\text{×}4\)

\(=36\text{×}5+36\text{×}4-36\text{×}6+36\text{×}4\)

\(=36\text{×}\left(5+4-6+4\right)=36\text{×}7=252\)

\(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{18}+\frac{1}{54}+\frac{1}{162}+\frac{1}{486}\)

\(3\times A=\frac{3}{2}+\frac{1}{2}+\frac{1}{6}+\frac{1}{18}+\frac{1}{54}+\frac{1}{162}\)

\(3\times A-A=\left(\frac{3}{2}+\frac{1}{2}+\frac{1}{6}+\frac{1}{18}+\frac{1}{54}+\frac{1}{162}\right)-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{18}+\frac{1}{54}+\frac{1}{162}+\frac{1}{486}\right)\)

\(2\times A=\frac{3}{2}-\frac{1}{486}\)

\(A=\frac{182}{243}\)

182/243

20,18 x 101 - 20,18

= 20,18 x (101 - 1)

= 20,18 x 100 = 2018

3,6 giờ x 5 + 216 phút x 2 + 3 giờ 36 phút x 3

= 3,6 giờ x 5 + 3,6 giờ x 2 + 3,6 giờ x 3

= 3,6 giờ x (5 + 2 + 3) = 3,6 giờ x 10 = 36 giờ

20.18 x 101 - 20.18 

= 20.18 x 101 - 20.18 x 1

= 20.18 x ( 101 - 1 )

= 20.18 x 100

=   2018

20,18 x 101 - 20,18

=20,18 x 100 + 20,18 x 1 -20,18

=2018           + 20,18 -20,18

=2018           + 0 = 2018          

Câu 1: 456 - 145 - 246

= ( 456 - 246 ) - 145

= 210 - 145

= 65

Câu 2: 162 x 10 + 37 x 10 + 10

= 10 x ( 162 + 37 + 1 )

= 10 x 200

= 2000

Câu 1 :

  456 - 145 - 246

= (456 - 246) - 145

= 210 - 145

= 65

Câu  2 :

  162 x 10 + 37 x 10 + 10

=10 x (162 + 37) + 10

= 10 x 199 + 10

= 1990 + 10

= 2000

câu 1:456 -145 -246

(456 -246) -145

210 -145

165

câu 2: 2000