Răspuns :
dif=4
201:4=50 rest 1=>şiruri consecutive 50 de numere
S=1+5+9+...+201
S=201+127+123+...+1
----------------------------------(+)
2S=202+202+202+...+202=>sunt 50 numere
2S=202×50
2S=10100
S=10100:2
S=5050
201:4=50 rest 1=>şiruri consecutive 50 de numere
S=1+5+9+...+201
S=201+127+123+...+1
----------------------------------(+)
2S=202+202+202+...+202=>sunt 50 numere
2S=202×50
2S=10100
S=10100:2
S=5050