Presence of Mind:Interview

• Interviewer: (Scribbles something on the paper) Prove this.
• Me: It is against the laws of mathematics. The only way out is to fool you.

I was asked to prove 5–2=4.

• Interviewer: It is a trick question and the clock is ticking.
• Me: (One minute passes)…
• Me: (Two minutes pass)…
• Me: (Three minutes pass)…
• Interviewer: Got anything?
• Me: I think I got something.

This is what I did

Explanation :

Consider each line segment as a stick. 5–2 becomes 4 since 0 is made up of 4 sticks.

Also 5 and 2 have 5 sticks each. So the no. of sticks in 5 minus the no. of sticks in 2 equals zero, the number in RHS.

Her solution was-

1. She wrote FIVE.
2. She striked off two letters since it was 5–2. The two letters remaining were IV.
3. As we all know, IV represents 4 in Roman.

This experience was one-of-a-kind

There were some more instances in the same interview which had to be dealt similarly but let's leave that for some other time.