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A recent maths puzzle on Youtube and how the answer was worked out:
https://www.youtube.com/watch?v=Zz-xOjyTxHI
Puzzle was to work out the square root of (10 times 11 time 12 times 13 and then plus 1).

I was able to work it out in a somewhat different way,
12 times 13 is 12 times 12 plus 12 so 156.
156 times 11. Last digit is a 6. Last but one digit is 5 + 6 so 11 so 1 with a carry back of 1 (=10). Last but 2 digits is 1 plus 5 plus that 1 carry back so 7. First digit is 1. That makes 156 time 1716
1716 time 10 is 17160.
17160 plus 1 is 17161.

So what's the square root of 17161?
Has 5 digits so the square root has to have 3 digits and may have digits after the decimal point.
So to make it simpler, deal with the first 3 digits of 17161 so 171,
Square of 10 is 100, of 11 121 and of 12 144. To get to the square of 13 take the 144 add 12 and 13 which comes to 169.
Square of 14 is 169 plus 13 plus 14 equals 196. 171 is above 169 but below 196.
So the square root has to start with 13.
As the square of 13 is 169, the square of 130 is 16900.
So using the same method as above. The square of 131 is 16900 plus 130 plus 131 which comes to 17161, the number I worked out above. So there's no digits after the decimal point and the answer is 131.

El Loro
@El Loro posted:

A recent maths puzzle on Youtube and how the answer was worked out:
https://www.youtube.com/watch?v=Zz-xOjyTxHI
Puzzle was to work out the square root of (10 times 11 time 12 times 13 and then plus 1).

I was able to work it out in a somewhat different way,
12 times 13 is 12 times 12 plus 12 so 156.
156 times 11. Last digit is a 6. Last but one digit is 5 + 6 so 11 so 1 with a carry back of 1 (=10). Last but 2 digits is 1 plus 5 plus that 1 carry back so 7. First digit is 1. That makes 156 time 1716
1716 time 10 is 17160.
17160 plus 1 is 17161.

So what's the square root of 17161?
Has 5 digits so the square root has to have 3 digits and may have digits after the decimal point.
So to make it simpler, deal with the first 3 digits of 17161 so 171,
Square of 10 is 100, of 11 121 and of 12 144. To get to the square of 13 take the 144 add 12 and 13 which comes to 169.
Square of 14 is 169 plus 13 plus 14 equals 196. 171 is above 169 but below 196.
So the square root has to start with 13.
As the square of 13 is 169, the square of 130 is 16900.
So using the same method as above. The square of 131 is 16900 plus 130 plus 131 which comes to 17161, the number I worked out above. So there's no digits after the decimal point and the answer is 131.

I can’t even follow the instructions El

Baz

@slimfern a couple of films on the Talking Pictures tv channel during the coming week.

The lesser one is on Wednesday at 18.30. It's "Bulldog Drummond Escapes" (1937). I don't think it;s one of the better ones in that series but is of note as the lead was played by Ray Milland.

The more notable one is next Sunday at 18.30, It's "Meet John Doe" (1941). Directed by Frank Capra and starring Gary Cooper and Barbara Stanwyck. You may have seen this before but a long time ago. Radio Times review doesn't think much of the film but other reviewers rate it as worth watching, for instance imdb has a rating of 7.6.

El Loro
@El Loro posted:

@slimfern a couple of films on the Talking Pictures tv channel during the coming week.

The lesser one is on Wednesday at 18.30. It's "Bulldog Drummond Escapes" (1937). I don't think it;s one of the better ones in that series but is of note as the lead was played by Ray Milland.

The more notable one is next Sunday at 18.30, It's "Meet John Doe" (1941). Directed by Frank Capra and starring Gary Cooper and Barbara Stanwyck. You may have seen this before but a long time ago. Radio Times review doesn't think much of the film but other reviewers rate it as worth watching, for instance imdb has a rating of 7.6.

Thankyou El

Gary Cooper & Barbra Stanwyck....that's a good coupling ...might give that one a watch

slimfern
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