Tính nhanh: h. ( -16 ) . 7. ( -5 ) i. 4. ( -31 ) . ( -125 ) k. 42 . ( -5 ) . ( -20 )

h. ( -16 ) . 7. ( -5 )

= [( -16 ) . ( - 5 )] .7

= 80 . 7

= 560

i. 4. ( -31 ) . ( -125 )

= [ 4 . ( -125 )] . ( -31 )

= -500 . ( -31 )

= 15500

k. 42 . ( -5 ) . ( -20 )

= 42 . [( -5 ) . ( -20 )]

= 42 . 100

= 4200

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