Hey agn.
Not exactly Mona.
Do you know what exactly a hexadecimal no. is? if no, then I think you got to a brush on it a lil bit. and yes then the d does not represent a decimal but its no in whole(00000d) which means 13. And as for unicode, 'u' after the escape character(\) mean its a unicode character. If you wanna know about unicode u can reach
Unicode web page but If you can understand a single part of it, you are a real pro.
.Bur yeah u got to know wat unicode and hex nos. are.
If in doubt agn. you can ask agn. lolz.
Kind Regards,
Anish Doshi.