There are 2015 marbles in a box. The marbles are numbered from 1 to 2015. Marbles with equal
digit sums have the same colour and marbles with different digit sums have different colours.
How many different colours of marbles are there in the box?
Marbles with digit sum $1=(1,10,100,1000)$
Marbles with digit sum $2=(2,11,20,101,110,200, .2000)$
Maximum digit sum possible when number $=1999$
Digit Sum here is 28
Hence starting from 1 to 28 , one can get 28 different colored marbles.
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