Originally Posted by
quantify
Can someone please explain how to do big division quickly in your head? I can simplify some fractions, but struggle with others.
You burn 150 kgs of fuel per hour. How much fuel will you need to travel 754 miles if you average a speed of 870 mph?
how do you divide the fraction of 754/870
You travel at an average speed of 190 mph. How much fuel do you need for a 114 mile trip if you burn 50 kgs per hour?
how do you simplify 114/190? I get it will become 57/95 after which I get stuck. Any help would be great, thanks.
I’d use the fact that 60mph is a mile a minute, then work from there.
1. 870 mph is 14.5 miles per minute. (14*6 = 84 and half of 6 gets you the remaining 3 to get 87) use a factor of 10 to make the numbers smaller.
14.5 miles a minute, is 1450 miles in a 100 minutes. Half of 1450 is 725. So, in 50 minutes we cover 725 miles (nearly there) Add another 2 minutes at 14.5 miles per minute gets you to 753 and 52 minutes. Close enough. That’s .9 (ish) of an hour. .9 of 150 kg is 135kg.
They’ve given you numbers that work with mile/minute and it’s multiples. If it’s multiple choice, then you wouldn’t have to be so precise. Mile a minute, 3 times descent rates, and maybe 1 in 60 are some of the techniques that have a practical application. Most pilots are good at their 6 times tables.
There’s probably also a clever way to do it. I’m not clever
