Question

10+20+30+40+50+60+70+80+90+100

Answer 1

10+20+........+100

=(100+10)+(20+90)+(30+80)+(40+70)+(50+60)

=110+110+110+110+110

=110 x 5

=550

Answer 2

=(10+90)+(20+80)+(30+70)+(40+60)+50+100

=100+100+100+100+50+100

=550

Answer 3

(10+90)+(20+80)+(30+70)+(40+60)+100+50

=100+100+100+100+100+50

=200+100+100+100+50

=300+100+100+50

=400+100+50

=500+50

=550

Answer 4

( 10 + 90 ) + ( 20 + 80 ) + ( 30 + 70 ) + ( 40 + 60 ) + 50 + 100

= 100 + 100 + 100 + 100 + 100 + 50

= 100 X 5 + 50

= 500 + 50

= 550