Question

Aflați diferența dintre suma tuturor numerelor de doua cifre identice si suma numerelor formate numai din zeci .

Answer 1

11-10 22-20 33- 30 44-40 55-50 66-60 77-70 88-80 99-90

Answer 2

(11+22+33+44+55+66+77+88+99)-(10+20+30+40+50+60+70+80+90) =
(33+33+44+55+66+77+88+99)-(30+30+40+50+60+70+80+90)=
(66+44+55+66+77+88+99)-(60+40+50+60+70+80+90)=
(110+55+66+77+88+99)-(100+50+60+70+80+90)=
(165+66+77+88+99)-(150+60+70+80+90)=
(231+77+88+99)-(210+70+80+90)=
(308+88+99)-(280+80+90)=
(396+99)-(360+90_=
495-450= 45