So I tried
numeral(30).format('0,00.0000000000000000000000000a')
and answer is '29.9999999999999964472863212'
surprisingly when I add one more zero to formatting the answer is correct.
numeral(30).format('0,00.00000000000000000000000000a')
'30.00000000000000000000000000'
please fix this issue.