An arithmetic teaser
Aug 23rd 2016, 1:48 pm
#1
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An arithmetic teaser
I read this the other day so I pass it on.
Question: can you add all the numbers between 1 and 100 together in your head?
Most people can't do it but it's easy if you have a method (which I couldn't come up with at the time when I read it I freely admit).
The answer is 5,050 and the method goes:
1 + 100 = 101; 2 + 99 = 101; 3 + 98 = 101 ............ i.e. 50 pairs of 101 = 5,050.
Similar contributions welcomed.
Question: can you add all the numbers between 1 and 100 together in your head?
Most people can't do it but it's easy if you have a method (which I couldn't come up with at the time when I read it I freely admit).
The answer is 5,050 and the method goes:
1 + 100 = 101; 2 + 99 = 101; 3 + 98 = 101 ............ i.e. 50 pairs of 101 = 5,050.
Similar contributions welcomed.
Aug 25th 2016, 11:14 am
#2
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Re: An arithmetic teaser
The pub quiz - annoying us with useless facts that have zero application in real life 
Aug 25th 2016, 11:16 am
#3
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Aug 25th 2016, 11:17 am
#4
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Re: An arithmetic teaser
26 + 6 = 1. Explain.
Aug 25th 2016, 12:09 pm
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Aug 25th 2016, 12:24 pm
#8
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Aug 27th 2016, 7:00 am
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Re: An arithmetic teaser
Aug 27th 2016, 7:47 am
#12
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Re: An arithmetic teaser
So 2 for 1919 is correct.
My first primary teacher used to say how many fingers and thumbs do have on both hands? Class all shouted 10. OK he said, taking left hand, pointing to thumb and saying 10, 9, 8, 7 and 6 plus how many on the other hand? 5 the class shouted. So, 6 and 5 equals? 11 the class shouts scratching heads.
Aug 27th 2016, 9:24 am
#13
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Re: An arithmetic teaser
My method was too find the middle number, which would be the average, and multiply by 100. The middle number is 50.5, as the list of numbers is even. 50.5 x 100 = 5,050
Aug 29th 2016, 2:36 am
#15
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Re: An arithmetic teaser
So three builders decide they are going to buy a radio for $30 and put in $10 each. They send the apprentice to buy it, but when he gets to the shop there's a sale on, $25 instead of $30. He pays the money and decides to keep some for himself, he decides $2 for himself and a dollar each change for the builders.
So the builders end up paying $9 each, the apprentice has taken $2 for himself. 3 x9 = 27, + 2 = 29. Where's the other dollar gone ?
So the builders end up paying $9 each, the apprentice has taken $2 for himself. 3 x9 = 27, + 2 = 29. Where's the other dollar gone ?