15673-X+145=13675

X+145=15673-13675

X+145=1998

X=1998-145

X=1853

a) 325 x 145 + 145 x 475 + 145 + 145 x 199 = 145 x (325+475 + 1 +199)

= 145 x 1000 = 145000

Đ

ĐÚNG!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Đ

=145x(1+2+1)=145x4=580

145+145X145+145= 145x4=580

tính nhanh

145 + 145 x 2 + 145

=190+190

=380

Phân phối:

= ( 145 x 99 + 145 x 1 ) - ( 143 x 101 - 143 x 1 )

= 145 x (99 + 1) - [143 x (101 - 1)]
= 145 x 100 - 143 x 100
= (145 - 143) x 100
= 2 x 100 = 200

\(a.145\times565+145\times54+56\times145\)

\(=145\times\left(565+54+56\right)\)

\(=145\times675\)

\(=97875\)

\(b.225\times104\)

\(=\left(100+4\right)\times225\)

\(=22500+900\)

\(=23400\)

\(c.1000:\left(20\times25\right)\)

\(=1000:500\)

\(=2\)

\(d.\left(206\times20\right):2\)

\(=206\times\left(20:2\right)\)

\(=206\times10=2060\)

a) Tính bằng cách thuận tiện nhất:

134 x 4 x 5

= 134 x (4 x 5)

= 134 x 20 = 1680

5 x 36 x 2

= 36x (5 x 2)

= 36 x 10 = 360

42 x 2 x 7 x5

= (42 x 7) x (2 x5)

= 294 x 10 = 2940

b) 137 x 3 + 137 x 97

= 137 x (3 + 97)

= 137 x 100 = 13700

94 x 12 + 94 x 88

= 94 x (12 + 88)

= 94 x 100 = 9400

428 x 12 - 428 x 2

= 428 x (12 - 2) = 4280

537 x 39 - 537 x 19

= 537 x (39 - 19)

= 537 x 20 = 10740

=145x(99+1)-143x(101-1)

=145x100 - 143x100

=100x(145-143)

=100x2

=200