divisibility of checking 4 the last two number should be multiple of 4
2345 >>> 45 not a multiple of 4
4512 >>> 12 is a multiple of 4
1728 >>> 28 is a multiple of 4
3241 >>> 41 is not a multiple of 4
checking divisibility of 9 the sum of number should be th multiple of 9
4512 >>>> 4+5+1+2=12 not a multiple of 9
1728 >>>> 1+7+2+8=18 is a multiple of 9