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.
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Puzzle 200
Hidden in the grid below are eight, 7-letter words. Each word begins with the central R and you can move one letter in any direction to the next letter. All of the letters are used exactly once each. What are the words?
T
A
E
R
O
B
O
E
T
G
S
T
N
W
R
N
E
E
A
I
E
I
N
U
R
E
F
R
N
B
U
O
E
E
E
B
S
E
A
E
V
E
I
D
H
T
S
G
N
Note: this puzzle is not interactive, and the letters cannot be clicked.
