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The Button That Blows Out Candles

A calculator curiosity

A true story.  Many years ago, an elderly man shuffled up to me during a break at a conference.

"Do you know about the calculator button that blows out candles?" he asked.  I didn't.

He reached into his pocket and pulled out a calculator and a crumpled piece of paper.  Drawn on the paper were ten boxes, numbered zero to nine.  "There are different coloured candles in each box," he said. "Would you like to choose a colour?"

"Er, yellow?"

"Excellent choice, yellow is in box three.  He pretended to take out a yellow candle and light it, and tapped '3' on the calculator.  "Next colour?"


"Box nine!"  He tapped 9 on the calculator, which now displayed '39'.

I continued to choose colours.  Purple (in box zero, it turned out), White (box 6), Green (2) and finally Orange (box 5).

"So here are your six candles: 390625," he said.  "Now blow them out."  He held his thumb over the candle-blowing button and I blew.  Three of the numbers, 390, disappeared.  "Have another go."  I blew again, and the 6 disappeared.  "Blow harder."  The 2 disappeared.

"Alright, one final big puff," he said, subtly shifting his thumb to another key.  I blew one more time and the final candle, the 5, disappeared.

I never saw that man again, but I've not forgotten his lovely little candle curiosity.

The Button That Blows Out Candles