I can't remember all these key sequences so I am adding this as a post in my blog, I guess this will be pretty useful for many...!!!
HOW TO MAKE SYMBOLS WITH KEYBOARD
Alt + 0153..... ™... trademark symbol
Alt + 0169.... ©.... copyright symbol
Alt + 0174..... ®....registered trademark symbol
Alt + 0176 ...°......degre e symbol
Alt + 0177 ...±....plus-or -minus sign
Alt + 0182 ...¶.....paragr aph mark
Alt + 0190 ...¾....fractio n, three-fourths
Alt + 0215 ....×.....multi plication sign
Alt + 0162...¢....the cent sign
Alt + 0161.....¡..... .upside down exclamation point
Alt + 0191.....¿..... upside down question mark
Alt + 1.......☺....sm iley face
Alt + 2 ......☻.....black smiley face
Alt + 15.....☼.....sun
Alt + 12......♀.....female sign
Alt + 11.....♂......male sign
Alt + 6.......♠.....spade
Alt + 5.......♣...... Club
Alt + 3.......♥...... Heart
Alt + 4.......♦...... Diamond
Alt + 13......♪.....eighth note
Alt + 14......♫...... beamed eighth note
Alt + 8721.... ∑.... N-ary summation (auto sum)
Alt + 251.....√.....square root check mark
Alt + 8236.....∞..... infinity
Alt + 24.......↑..... up arrow
Alt + 25......↓...... down arrow
Alt + 26.....→.....right arrow
Alt + 27......←.....left arrow
Alt + 18.....↕......up/down arrow
Alt + 29......↔...left right arrow