Question

1+2+3+...+98+99+100=

Answer 1

1+2+3+...+98+99+100
=100·(100+1):2=
=100·101:2=
=10.100:2
=5.050

Am aplicat formula ptr suma lui gauss : n·(n+1):2

Answer 2

Răspuns

Explicație pas cu pas:

1 + 2 + 3 + ..... + 98 + 99 + 100 = 5 050

= 100 × ( 1 + 100 ) : 2 =

= 100 × 101 : 2 =

= 10 100 : 2 =

= 5 050

____________________

sau aplic asociativitatea:

( 1 + 100 ) + ( 2 + 99 ) + ( 3 + 98 ) + ........ + ( 49 + 52 ) + ( 50 + 51 ) =

= 50 × 101 =

= 5 050