a ) A = 5 6

b ) B = 10 39 c ) C = 1 3.5 + 1 5.7 + 1 7.9 + 1 9.11 + 1 11.13 = 1 2 1 3 − 1 13 = 5 39

a: \(8\times427\times3+6\times573\times4\)

\(=24\times427+24\times573=24\times\left(427+573\right)\)

=24x1000

=24000

b: \(54\times47-47\times53-20-27\)

\(=47\times\left(54-53\right)-47\)

=47-47

=0

c: \(6\times1235\times20-5\times235\times24\)

=120x1235-235x120

=120x1000

=120000

d: \(\left(137\times99+137\right)-\left(17\times101-17\right)\)

\(=137\times\left(99+1\right)-17\times\left(101-1\right)\)

=137x100-17x100

=13700-1700

=12000

e: \(\left(145\times99+145\right)-\left(143\times101-143\right)\)

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

=14500-14300

=200

g: \(\left(2003-123\times8:4\right)\times\left(36:6-6\right)\)

\(=\left(2003-123\times2\right)\times\left(6-6\right)\)

=0

C = 1 3.5 + 1 5.7 + 1 7.9 + 1 9.11 + 1 11.13 = 1 2 1 3 − 1 13 = 5 39

1. 1234 + 5678 + 4321 + 8765

= (1234 + 8765) + (5678 + 4321)

= 9999 + 9999

= 19998

2. 1357 + 2468 + 8642 + 7531

= (1357 + 8642) + (2468 + 8642)

= 9999 + 11110

= 21109

3. 19991999.1998 - 19981998.1999

= 19991999.1998 - 19981998.1998 - 19981998

= 1998.(19991999 - 19981998) - 19981998

= 1998.10001 - 1998.10001

= 0

8765+1234=9999 

HT 

k cho mình nha

TL:

= 9999

_HT_

a) 6*1235*20-5*235*24 = 120(1235-235)=120.1000=120000

b) =[145*99+145*1]-[143101*1]=145*[99+1]-145*[101-1]=145*100-143*100=100*[145-143]=100*2=200

Đáp án B