a)  ( − 25 ) .11 = ( − 25 ) . ( 10 + 1 ) = − 25.10 + ( − 25 ) .1 = − 250 + ( − 25 ) = − 275

b)  31. ( − 99 ) = 31. ( − 100 + 1 ) = 31. ( − 100 ) + 31.1 = − 3100 + 31 = − 3069

c)  ( − 8 ) .130 = ( − 8 ) . ( 125 + 5 ) = ( − 8 ) .125 + ( − 8 ) .5 = − 1000 + ( − 40 ) = − 1040

d)  25. ( − 14 ) = 25. ( − 10 ) + ( − 4 ) = 25. ( − 10 ) + 25. ( − 4 ) = − 250 + ( − 100 ) = − 350

  − 63.41 = − 63. 40 + 1 = − 63.40 + − 63 .1 = − 2520 − 63 = − 2583

  − 53.21 = − 53. ( 20 + 1 ) = − 53.20 + ( − 53 ) .1 = − 1060 + − 53 = − 1103

25. ( − 14 ) = 25. ( − 10 ) + ( − 4 ) = 25. ( − 10 ) + 25. ( − 4 ) = − 250 + ( − 100 ) = − 350

(–57) . 11

= (–57) (10 + 1) (tách 11 = 10 + 1).

= (–57 ) . 10 + (–57 ) . 1 (áp dụng tính chất phân phối của phép nhân)

= –570 + (–57 ) = –(570 + 57) = –627;

75 . (–21)

= 75 . (–20 – 1) (tách –21 = –20 –1)

= 75 . (–20) – 75.1 (áp dụng tính chất phân phối của phép nhân và phép cộng)

= –1500 – 75

= –1575

    22.(-99)

= 22.(1-100)

= 22 - 2200

= -2178.

( − 25 ) .11 = ( − 25 ) . ( 10 + 1 ) = − 25.10 + ( − 25 ) .1 = − 250 + ( − 25 ) = − 275