# Maths Make It True

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

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

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

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

• 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? – Rubio Feb 23 '17 at 6:37
• The other answer didn't say how it was found – ULTIMATEGAMER07 Feb 23 '17 at 6:38
• @ULTIMATEGAMER07, regardless, you could have just commented with an explanation. – boboquack Feb 23 '17 at 8:23