Use remainder method to convert the decimal (base-10) to the hexadecimal (base-16). Divide the given decimal, 321.143, into two parts: one is whole number part, 321, and the other is following fractional part, 0.143.

In whole num. part, the decimal num., 321, is devided successively by the base of hexadecimal, 16, until the quotient is zero. The hexadecimal num. is found by taking the remainders in the reverse order. 321÷ 16=20 R1, 20÷16=1 R4, 1÷16=0 R1 Therefore the hexdecimal num. for 321 is 141.

In fractional part, the decimal fraction, 0.143, is multiplied successively by 16. The hexadecimal fraction is formed from the integer part of the products taken in the same order in which they were determined. 0.143×16=2.288, 0.288×16=4.608, 0.608×16=9.728, 0.728×16=11.648, 0.648×16 =10.368, 0.368×16=5.888, 0.888×16=14.208

Since 10,11 and 14 in decimal num. are A,B and E in hexadecimal num. respectively. Thus the hexdecimal fraction for decimal fraction, 0.143, is 0.249BA5E. Therefore, the hexadecimal representation of decimal 321.143 is 141.249BA5E. In the same manner, the octal representation of decimal 321.143 is 501.1111564.