Reasoning
1,000 in Roman numerals.
X = 10
L = 50
C = 100
D = 500
M = 1,000
?
Puzzle 58
The BrainBashers football world tour is well underway and Alex is planning the journey to each country.
Unfortunately, the BrainBashers atlas software is playing up again and has worked out the mileage incorrectly, as shown below.
China 3,500
Finland 6,000
Chile 3,700
Jamaica 3,800
Wales 6,000
According to the software, how many miles is it to Germany?
Answer
If the sum of the digits is divisible by nine, so is the number.
Add up all of the digits in the number and see if the sum is divisible by 9. If you still can't tell, you can add those digits again to see if the new sum is divisible by 9. You can keep going until you the sum is obviously divisible by 9 or not.
For example, is 486451464 divisible by 9?
Do 4 + 8 + 6 + 4 + 5 + 1 + 4 + 6 + 4 = 42.
Is 42 divisible by 9? Not sure, you can then do:
4 + 2 = 6. Which clearly isn't divisible by 9. So our original number, 486451464, isn't either.