Question

Calculează suma tuturor numerelelor nenule care impartite la 20 dau catul egal cu sfertul restului

Answer 1

D=?
D=o
I=20
C=R:4
R=Cx4
D=IxC+R  R<I
D=20xC+R  R<20
R=4,8,12,16
R=4  D=20x1+4=24
R=8 D=20x2+8=48
R=12 D=20x3+12=72
R=16 D=20x4+16=96
 SUMA- 24+48+72+96=240

Answer 2

D:20=C, rest R
C=R:4 =>R=4C
R<20 =>R={1,2,...,19}
20C+4C=D
24C=D
Daca C=1 =>D=24 -->24:20=1, rest 4
Daca C=2 =>D=48 -->48:20=2, rest 8
Daca C=3 =>D=72 -->72:20=3, rest 12
Daca C=4 =>D=96 -->96:20=4, rest 16
Daca C=5 =>D=120 -->120:20=6, rest 0 NU ESTE BUN

=>24+48+72+96=240