Răspuns:
a) 74×99=74×(100-1)
=74×100-74×1
=7400-74
=666
b) 58×99=58×(100-1)
=58×100-58×1
=5800-58
=5742
c) 63×11=63×(10+1)
=63×10+63×1
=630+63
=693
d) 56×11=56×(10+1)
=56×10+56×1
=560+56
=616
