a) ( 11 x 8 - 100 + 12 ) : ( 4 x 5 x 6 x 7 x 8 x 9 x 10 )
= ( 88 +12 - 100 ) : ( 4 x 5 x 6 x 7 x 8 x 9 x 10 )
= ( 100 - 100 ) : ( 4 x 5 x 6 x 7 x 8 x 9 x 10 )
= 0 : ( 4 x 5 x 6 x 7 x 8 x 9 x 10 )
= 0
b) ( 132 x 6 - 66 x 12 ) x ( 132 x 6 + 66 )
= ( 11 x 12 x 6 - 66 x 12 ) x ( 132 x 6 + 66)
= ( 66x 12 - 66 x 12 ) x ( 132 x 6 + 66 )
= 0 x ( 132 x 6 + 66)
= 0
c) Có: (100 - 2) : 1 + 1 = 99 ( số)
100 - 99 + 98 - 97 + 96 - 95 + ... + 4 - 3 + 2
= ( 100 - 99 ) + ( 98 - 97) + ( 96 - 95) + ... + ( 4 - 3) + 2 ( 49 cặp 2 số, thừa số 2 )
= 1 + 1 + 1 + ... + 1 + 2 ( 49 số 1)
= 49+2
= 51