Here is a link to chewing gum from Amazon:
Extra Chewing Gum, Sugar Free, Peppermint Flavour, 30 Packs of 10 Pieces https://www.amazon.co.uk/dp/B0025UOJ6E/ref=cm_sw_r_cp_api_glt_fabc_7M40MWXJ0D3F88FFTHPJ
1 box has 30 packs .
1 box costs £10. That means each pack costs 33p
You are going to sell it to your fellow pupils at school for £1 each. That gives you a profit of around 66p per pack. That means per box you will get £30 but only £20 will be profit because you spent £10 on buying the box.
You will need to sell 33 boxes to make £1000.
It means you have to sell 990 packs of chewing gum for £1 each, if you sell 5 packs a day which is £5 then it will take you a little over 6 months. If you sell 10 pack then you will have the £1000 in 3 months.
Now you could also buy other stuff too and sell that along side your chewing gum. You could sell pens, drinks, crisps etc.
Chewing gum is good because secondary school kids love it and it’s small to carry round so the teachers don’t clock on. Plus there is always some kid asking for gum. You could charge the kids more if you want lol.
Don't worry about that, worry about your breath after all that snuff.
Here's some help King halitosis