Hi Deepak. Shotgun ammo varies in length and payload from manufacture to manufacturer and from product to product. For instance, some 70mm SG have 7 pellets, while the same company makes a very similar round that has 9 pellets. The easiest way to determine the answer is to simply note how many pellets there are per ounce in each size. All shotgun ammo will have the shot WEIGHT clearly printed on the box. You can then just "do the math" and get your answer.
1-LG (in the US "000") 6 pellets/ounce
2-SG (in the US "00") 8 pellets/ounce
3-SSG (in the US "2 Buck") 14 pellets/ounce
4-00 Buck is SG and as above has 6 pellets/ounce
5-Number 1 (Special LG in the UK) 11 pellets/ounce