Question

Determinati suma numerelor naturale mai mari sau egale cu 90 si mai mici decat 163.​

Answer 1

$90 \leqslant numere < 163$

=> Numerele sunt: 90,91,92,...,162

S= 90+91+92+....+162

S= 162+......90+91+92

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2S= 252+..............+252

Numar termeni: (162-90)+1= 72+1=73( termeni)

=> S= 252×73 :2

S= 18.396:2

S= 9.198