Răspuns :
Mai intai rezolvam paranteza aplicand formula lui Gauss: n[(n+1)/2]
1+2+3+...+23=
n=23
23[(23+1)/2]=
23×24/2=
23×12=276
900-276-m=98
624-m=98
m=624-98
m=526
900 - ( 1 + 2 + 3 + ..... + 23 ) - m = 98
900 - ( 23 × 24 : 2 ) - m = 98
900 - ( 552 : 2 ) - m = 98
900 - 276 - m = 98
624 - m = 98
m = 624 - 98
m = 526
900 - ( 23 × 24 : 2 ) - m = 98
900 - ( 552 : 2 ) - m = 98
900 - 276 - m = 98
624 - m = 98
m = 624 - 98
m = 526