The least number to be added to the numbers to make them divisible by 9 is equal to the difference of the least multiple of 9 greater than the sum of the digits and sum of the digits.Sum of digits = 15.Nearest multiple of 9 greater than sum of digits = 18.Hence 3 has to be added.
Let the number of children be 'x' Therefore, each child will receiveX x 60/100 = 3x/5 chocolates∴ X x 3x/5 = 735∴ x² x 735x5/3 = 1225∴ x = 1225 = 35∴ Number of chocolates = 3x/5 = 21