Calculator Fun VCCalculator Fun VCCalculator Fun VCCalculator Fun VCLiss Junior SchoolLiss Junior School

2626thth February 2008 February 2008

We had fun working with calculators back

in class.

Here are our presentations about

the work we did.

THE FIRST MECHANICAL CALCULATOR

• The first calculator was called a Curta calculator which was used in the second world war and was used to count prisoners in a concentration camp.

• It was invented by Curt Herzstark.

The first calculator to be used in shops.

• To the right of you is a mid 19th century calculator which was used all the time in shops to calculate how much all the objects costs together

What other mechanical calculators were there?• This Triumphator

CRN1 was used to print the answers to sums on pices of paper it was used by architects to calculate width, height and weight of buildings.

What other mechanical calculators were there?

• This Facit NTK is another example of a calculator.

• It was used by shop keepers and like the Triumphator CRN1 printed pieces of paper with the sum and answer on it.

“Reverse The Digits”

• First we had to turn the digits of a number around and then we had to find another number to take away so that made our first number be reversed.

• Of course we used a calculator to help us!

Turn 26 into 62

26 + 47 = 73 (too big!)

26 + 24 = 50 (too small)

26 + 36 = 62 √

Zach’s workings out• When we were trying to find the

calculation to turn the numbers around I found out a fact.

• If I took the number we started with away from the new number it gave me the answer!

• So by finding the difference between the two numbers I can find the answer quicker.

74 get to 47

74 – 47 = 27

74 – 27 = 47

Turn 156 into 651

651 – 156 = 495

156 + 495 = 651

I did this four times and my answers were right each time! My method

worked.

“One Million to Seven”

• We had to start with one million and turn it into seven, but you can only use these buttons: ÷ x - + 7 =

• You can use the buttons as many times as you like.

This was my answer:

1000000÷777777÷777777÷7777+ 7 =7

It took me a whole lesson to work this out with my friend Dino. We tried

lots of different ways but forgot to record them!

ISBN Investigation

• For this investigation, we were given some I.S.B.N numbers and had to work out if they were valid or not.

For instance:0-330-28987-X (the X symbolises ten). If that was the I.S.B.N number, then you would enter it into the grid on the next slide.

0 3 3 0 2 8 9 8 7 10 X

1 2 3 4 5 6 7 8 9 10 =

0 6 9 0 10 48 63 64 63 100

363

• Afterwards, we divided the answer (363) by 11 which give us 33 which means it’s it is a real I.S.B.N. We know this because it is a whole number, whereas some I.S.B.N numbers, once divided by 11, made a number point something. For instance, we tried to divide one number by 11 but it came out as 20.3636 recurring so it was a fake I.S.B.N number!