I noticed that many people are buying 100 shares per stock while investing. Is this a kind of strategy?

I do that for expensive shares. Totally understand it’s not cost effective. But it’s easier to get the foot in the door for a beginner.

(Was brought up old school by parent who prefer freehold to 99 years, so was uncomfortable with concept of custodian accounts.)

It is minimum lot size to buy over SGX. But need to check if it is cost effective for the brokerage fee to buy esp. for penny stock. I have a friend whose strategy (trade, not investing) is to buy 7-8k for a stock to reduce the cost effect via iOCBC (brokerage fee = $25)

That's the minimum lot size. You can't buy less.

There are only a few people who would do this.

1) To be able to own the stock. Jardine CC at $34.50. you need at least $3,450 just to buy 100 lots. Previously, it was $34,450 because minimum shares is 1,000.

2) Traders. They trade small amounts to accumulate at different spots and it will be compiled as 1 trade for the day.

3) To minimise commission. Some stocks are priced at $1. But to minimise commission, for most trades, you require stock price of $9,100 (for iOCBC) in order to pay only $25 (or 0.275%, whichever is higher). So people may enter 9,100 stocks to buy at $1.

4) RSP (Regular Savings Plan), which may be able to enter into a trade, but mostly it is just to facilitate the buying of shares.