Question

(1+2+3+…….+60)-(1+2+3+……40)=?

Answer 1

Răspuns:

( 1 + 2 + 3 + ....+ 60 ) - ( 1 + 2 + 3 + .....+ 40 ) = 1010

1 + 2 + 3 +.........+60 = 1830

S = ( 1 + 60 ) • 60 : 2

S = 61 • 60 : 2

S = 3660 : 2

S = 1830

1 + 2 + 3 + ........+ 40 = 820

S = ( 1 + 40 ) • 40 : 2

S = 41 • 40 : 2

S = 1640 : 2

S = 820

1830 - 820 = 1010