A decimal fraction such as ABCD.PQRST.... can be written as
Axx1000+Bxx100+Cxx10+D+P/10+Q/100+R/1000+S/10000+T/100000+.... in fraction or simply
ABCD+P/10+Q/100+R/1000+S/10000+T/100000+.............
As we have two digits in -0.33 (we are ignoring minus sign as it can be put later before equivalent fraction or percent immediately to the left of decimal point), it can be written as
3/10+3/100=(3xx10)/(10xx10)+3/100=30/100+3/100=33/100 and hence
-0.33=-33/100
To convert a fraction into percentage, just multiply it by 100 and percentage sign %. Hence
-0.33=-33/100=(-33/100xx100)%=-33%
