Puzzles for you

[indianbaba]

This thread made into Sticky. If it is not updated daily it will be removed.

@i_online, in view of making this thread sticky two of your puzzles have been added here and your original posts are moved.
Cheers
indianbaba.

[http://neerajsingh.bizhat]

Thanks indianbaba for making this thread sticky. It would surely help others.

Finger Multiplication
by Sidney Kolpas
Mathematics Teacher April 2002

It requires that the students hold both hands up, with palms facing the student. The student counts his or her thumbs and fingers consecutively
from left to right, with the thumb on the left hand representing the number 1 and the thumb on the right hand representing the number 10. To multiply n times 9, where 1 <= n <= 10 and where n is a whole number, the student bends down the nth finger. The number of fingers to the left of the bent finger represents the tens-place digit of the product, whereas the number of fingers to the right of the bent finger represents the ones-place digit of the product.

The figure below illustrates 7 x 9.




Mr. Kolpas explains why this works in his article in the April 2002 issue of the Mathematics Teacher.
Courtesy : http://www.pen.k12.va.us

[indianbaba]

i never knew that.
That was something marvellous.
Keep sharing.

[http://neerajsingh.bizhat]

Finger Multiplication by Nine
by Paul Horrell
Mathematics Teacher February 2003

The "finger folding" multiplication by 9 can be expanded to include multiplicands up to 99.

The algorithm used is similar to the following:

To multiply a two-digit number by 9, 
ENTER the multiplicand by forming a V between the tens-digit finger and the next finger to its right (SPREAD). 

ENTER the units digit by FOLDing the units-digit finger.

To read the product

Hundreds digit: Count the standing fingers before the SPREAD.

Tens digit: Moving from left to right, count the fingers from the SPREAD to the FOLD; wrap around if necessary.

Units digit: Count the standing fingers to the right of the FOLD.

Example:
48x9

Enter (1 2 3 4 _ 5 6 7 F 9 0)

   Read:
   Hundreds (1 2 3 4) 4
   Tens (5 6 7) 3
   Units (9 0) 2

Example with wraparound:
83 x 9

Enter (1 2 F 4 5 6 7 8 _ 9 0)

   Read:
   Hundreds (1245 6 78) 7
   Tens (9 0 1 2) 4
   Units (45 6 7890) 7

[http://neerajsingh.bizhat]

Climbing Snail

A snail is at the bottom of a 20 meters deep pit. Every day the snail climbs 5 meters upwards, but at night it slides 4 meters back downwards.
The Question: How many days does it take before the snail reaches the top of the pit?

[http://neerajsingh.bizhat]

Abracadabra with Apples

In Miss Miranda's class are eleven children. Miss Miranda has a bowl with eleven apples. Miss Miranda wants to divide the eleven apples among the children of her class, in such a way that each child in the end has an apple, but one apple still remains in the bowl.

The Question: Can you help Miss Miranda?

[http://neerajsingh.bizhat]

Chain Connection

You have five pieces of chain, each consisting of three links. You want to make one long chain of these five pieces. Breaking open a link costs 1 euro, and welding an open link costs 3 euros.

The Question: Is it possible to make one long chain of the five pieces, if you have just 15 euros?

[http://neerajsingh.bizhat]

$ THE MISSING DOLLAR RIDDLE $


Three friends check into a motel for the night and the clerk tells them the bill is $30, payable in advance. So, they each pay the clerk $10 and go to their room. A few minutes later, the clerk realizes he has made an error and overcharged the trio by $5. He asks the bellhop to return $5 to the 3 friends who had just checked in. The bellhop sees this as an opportunity to make $2 as he reasons that the three friends would have a tough time dividing $5 evenly among them; so he decides to tell them that the clerk made a mistake of only $3, giving a dollar back to each of the friends. He pockets the leftover $2 and goes home for the day! Now, each of the three friends gets a dollar back, thus they each paid $9 for the room which is a total of $27 for the night. We know the bellhop pocketed $2 and adding that to the $27, you get $29, not $30 which was originally spent. Where did the other dollar go????

[sohaibrazzaq]

Originally Posted by http://neerajsingh.bizhat

Climbing Snail

A snail is at the bottom of a 20 meters deep pit. Every day the snail climbs 5 meters upwards, but at night it slides 4 meters back downwards.
The Question: How many days does it take before the snail reaches the top of the pit?

If he has his fridge :shock: with lots of soda and something to eat with him then it will take him 16 Days to reach the top of the pit else he will starve to death ops:

Am i right :?:

[nokia-zone]

In jan 1 there was a lotus in a pond.
The number of lotus is doubled every night.And at last one day the pond was full of lotuses on jan 30.
Problem:-
When was the pond halfly filled,i need the date?