You can
put this solution on YOUR website! Yes, since 3 is a divisor.
An integer is a multiple of 3 if and only if the sum of all its
digits is a divisor of 3.
In fact , there is not necessary to add up all the digits, because
we can consider all mltiples of 3 as zeros and ignore them.
13346355645635645364562354623567
(ignore 3, 6) -->14554554545254257
(ignore 45,54,57) -->15522
(ignore 15) -->522
(sum of all digits = 9) --> the origin huge number is a multiple of 3.
After more practice, you can check if a given integer is equal to
0 mod 3 faster.)
If you want to test if it is a multiple of 9.
(Ignore 45, 63,36 and 54)--> 1334556635662354623567
(Ignore 45, 63,36, 54 )--> 1335656623623567
(Ignore a pair of (3 ,6) , (4,5) & (2,7)) --> 155625
(Ignore 162) -> 555 --> sum = 15 --> sum= 1+5= 6
--> multiple of 3 (but not 9)
Kenny
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