2
$\begingroup$

Change one of the $+$ signs to an equals sign so that you create an addition problem with a true answer:

$$\text{1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20}$$

$\endgroup$
3
$\begingroup$

Assuming the 2- is actually 20...

1+2+3+4+5+6+7+8+9+10+11+12+13+14
=
15+16+17+18+19+20

$\endgroup$
2
$\begingroup$

Easy:

put '=' in between 14 and 15 ie
1+2+3+4+5+6+7+8+9+10+11+12+13+14=15+16+17+18+19+20

Easy way to find out N(N+1)/2 =

(20*21)/2 - N(N+1) /2

$\endgroup$
  • $\begingroup$ You might want to look at other answers already given before adding one of your own. How does your answer materially differ from the existing one? $\endgroup$ – Rubio Feb 23 '17 at 6:37
  • 1
    $\begingroup$ The other answer didn't say how it was found $\endgroup$ – ULTIMATEGAMER07 Feb 23 '17 at 6:38
  • $\begingroup$ @ULTIMATEGAMER07, regardless, you could have just commented with an explanation. $\endgroup$ – boboquack Feb 23 '17 at 8:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.