Observe the following:
1 + 2 – 3 + 4 + 5 – 6 – 7 + 8 – 9 = –5

Change one ‘–’ sign as ‘ + ’ sign to get the sum 9.

Question

Observe the following: 1 + 2 – 3 + 4 + 5 – 6 – 7 + 8 – 9 = –5 Change one ‘–’ sign as ‘ + ’ sign to get the sum 9.

Philoid · Accepted Answer

We can observe that,

⇒ 1 + 2 – 3 + 4 + 5 – 6 – 7 + 8 – 9

⇒ (1 + 2 – 3) + (4 + 5 – 9) – 6 – 7 + 8

⇒ 0 + 0 + 2 – 7

⇒ 2 – 7

If we change the sign of 7 from ‘–’ to ‘ + ’ it would become,

⇒ 2 + 7

⇒ 9

Observe the following:1 + 2 – 3 + 4 + 5 – 6 – 7 + 8 – 9 = –5Change one ‘–’ sign as ‘ + ’ sign to get the sum 9.