aflam suma lui gauss pentru numerele pare
S1=2+4+6+...+30
S1=30+28+26+...+2
2S1=32+32+32+...+32
2S1=32*[(30-2):2+1]
2S1=32*15
2S1=480
S1=480:2
S1=240
AFLAM SUMA LUI GAUSS PENTRU NUMERELE IMPARE
S2=1+3+5+...+29
S2=29+27+25+...+1
2S2=30+30+30+...+30
2S2=30*[(29-1):2+1]
2S2=30*15
2S2=450
S2=450:2
S2=225
S1-S2=240-225=15