Hi Mike.
You’ve got the correct digits, but the number of ‘zeros’ or the ‘decimal-place’ needs to be adjusted !
… but not by as much as Ravvie’s 3 hours 
A completely different type of teaser … very straight forward, no hidden meanings, similar to a pub-quiz.
A film from 2000 portrayed the story of a young working-class boy’s ambition to become a ballet dancer.
Can you name the film ?
(1.8*10^11)/(2.4 *10^6)
= (1.8*10^5)/2.4
= 18000/2.4
= 7500 seconds
=125 mins
And… Billy Elliot?
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Hm, yes, did it in my head. Should be 7500 seconds.
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Billy Elliot is spot-on Bobby.
However, the download time for the app ………
……(I can see two separate errors in the calculation that you set out)
It took me quite a bit of effort to be sure I had the right number of zeros at each stage of the calcs. And after I saw your post and Mike’s I’ve re-checked and re-checked again …… and really hope that I haven’t goofed ……
Oops Mike, see my post to Bobby above.
If it’s any consolation, I had to write the numbers out long-hand. Then I rechecked using indecies.
75 so 
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Well done Mike.
I was helping my 14 year old grandson with some maths revision and that was one of the questions in his practise book. It took him a few attempts of muddling through before he took the necessary care to get the indecies correct. I thought then, that this might make a neat teaser
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Hi Bobby, I’ve no doubt that by now you’ve spotted where things need adjusting !
But for the benefit of others
The main one is 2.4GHz= 2.4*10^9 (not 10^6)
I thought i’d pull this one down before it evaporates into the ether …
- No, 1050
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I make it:
5 red
5 x 11 white
5 x 11 x 18 blue
Total 1050, but the trails disappeared before I could count them all to check my maths!
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Thanks, yes, I went back and spotted both of the issues. And unfortunately two wrongs didn’t make a right (one of my Mother’s mantras, vindicated!).
A real life brain teaser.
About 10 years ago, I bought a Georgian grandfather clock from an antiques shop. The label on the clock in the shop said 1770 (which I am sure is an approximation, of course).
A friend was at my house recently and we were drinking wine and chatting. The clock struck the hour (10 strikes, it was 10pm) and we got talking about it. We remarked on how it would have been made by candle light, that it had seen many monarchs, prime ministers, wars etc. Then my friend asked me: I wonder how many times the bell (chime) has been struck since it was new.
The clock only strikes the hour, not the half. Let’s assume it was commissioned and has been constantly in use since 1 June 1770.
How many times has the hammer struck the chime?
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Well, I get that 1st June 1770 was about 92,346 days ago. (as of 2nd April 2023 !!)
the clock strikes 1, 2, 3 … 11, 12 twice each day = 156 chimes per day
So we are talking about 14,405,976 chimes …
Ooopps … it’s just gone 10pm so another 10 chimes makes it 14,405,986 chimes.
(Also thought I should add the date of the calculation )
That’s more accurate than my effort:
2023 - 1770 = 253 years less April and May.
Approx 365.25 x (252 + 5/6) days.
(12+1)x12 = 156 strikes per day.
Just over 14.4 million strikes. Assuming it has been working correctly and continuously for over two and a half centuries!
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Well done Mike, (with the 1050).
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Well done Ravvie, and nicely explained too.
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Maybe answer ‘a’ is why the airline is called 50/50.
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Much more accurate than my first attempt. I did a first approximation without leap years or part years to use as a yard stick. Then when I went for my more accurate attempt I started to think about when leap years were introduced and got sucked into reading about that for a while. Then the anomaly about years divisible by 100 (but not 400) etc.
Once I’d navigated all that, I got to the same answer as you!
Also, as a cheaty “check sum” you can google “days since 1 June 1770”!
As an extra credit, I did wonder when strike number 15 million would occur…?
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