b= (7+7²+7³+7^4) + 7^5 (7+7²+7³+7^4) + 7^10n (7+7²+7³+7^4) +.................. 7^35 (7+7²+7³+7^4) + 7^40 (7+7²+7³)
Uc(7+7²+7³+7^4) =Uc(7+9 +3+1)=0⇒Uc(b) = 0+0+0+..+ Uc[7^40(7+7²+7³)] = Uc( 1+7+9+3)= 0 ⇒ Uc(b) =0 observatie: Uc(7^4k) =1
c= 1 +3+3²+3³+3^4 Uc(c) =Uc(1+3+9+7+1) = 1 Uc(c) = 1
d) 8^1 = 8 8²=64 8³=512 8^4 = ....6 ⇒ Uc(8+8²+8³+8^4) =0 ⇒ d = (8+8²+8³+8^4) + 8^5 (8+8²+8³+8^4) + ...........+8^84 (8+8²+8³+8^4)⇒ Uc(d) =0