Question

aflati toate numerele de forma abc care au ca ultima cifra 0 sau 5 si a la a doua egal cu 9. Calculati suma acestora

Answer 1

Numere:
300 305 310 315 320 325 330 335 340 345 350 355 360 365 370 375 380 385 390 395

unde
a = 3; pentru că 3 la puterea 2 = 9
b = {0,1,2,3,4,5,6,7,8,9,}
c = {0, 5}

Suma:
300+305+310+315+320+325+330+335+340+345+350+355+360+365+370+ +375+380+385+390+395=6950

Answer 2

abc = ab0    ab5   ala2=9   a=3
atunci  300,310,320,330,340,350,360,370,380,390,
            305,315,325,335,345,355,365,375,385,395

300+305+310+315+320+325+330+335+340+345+350+355+360+365+370+
+375+380+385+390+395=300+395x10=300+3950=4250