a. - 4² + ( -4) - ( - 1998 )° =
↓
= 1
= - 16 - 4 -1 = - 21
b. ( -5) :5 - 0⁴· 189= - 1
↓
= 0
c. [ 3⁴ : ( -3) ² + 2⁸ : ( -2) ⁵]¹⁹⁹⁹⁹ = [ 81 : 9 + 2⁸ : ( -1) ⁵ : 2⁵ ] ¹⁹⁹⁹⁹=
↓
= - 1
= [ 9 - 2⁸ ⁻ ⁵ ] ¹⁹⁹⁹⁹ = [ 9 - 2³ ] ¹⁹⁹⁹⁹ = [ 9 - 8 ] ¹⁹⁹⁹⁹ = 1¹⁹⁹⁹⁹ = 1