A few days ago, as I lay in bed dying of exhaustion from 30 minutes of playing with my niece and two nephews, I came up with an idea to keep them occupied.
"Can someone tell me what time it is?" I asked, as I peeled my younger nephew off my face.
"Oh, I know! I know!" my older nephew shouted, taking time out from hammering my laptop's keyboard. "It's... it's... three... one... o'clock!"
"No lah!" my niece chimed in. "It's three... five... o'clock!"
My younger nephew looked at the clock and stared blankly back at me.
"No, no, no. Think about it," I said, in between inspecting the bruises on my body.
It was actually 3.05pm, but more importantly, they had stopped trying to destroy my room and I could catch my breath for a while.
Fortunately, there are a few topics I have learnt that can be used to curb the excitement of young kids - time, colour and money for instance - because it is hard at their age to understand these abstract notions.
Unfortunately, I have recently realised I myself am struggling to understand money.
It is one of the problems I face living in a few different countries in quick succession, from Singapore to Malaysia to England to China.
As a result, I am sometimes a five-year-old boy who thinks that $49.90 is a perfectly reasonable price for a plastic robot, while other times, I am a 65-year-old auntie, who haggles with a hawker because the price of carrots went up by 20 cents this week.
Take, for example, this recent episode in Beijing.
I was in a rush to go somewhere one night with a friend from Singapore. So instead of waiting for a taxi, I stopped one of the many illegal motorised trishaws that ply the city's streets.
Since these vehicles are unlicensed, it was up to me to negotiate the fare with them, but I knew a taxi ride to our destination would cost less than 15 yuan (S$3.30).
"25 yuan," the trishaw driver told me.
"What?" I hollered. "Get lost."
"It's a fair price," he retorted. "Okay fine, 20 yuan."
"15 yuan. A taxi ride doesn't even cost that much," I said.
So there we were, arguing for about half a minute by the roadside when my Singaporean friend stepped in and said, "Okay, 20 yuan, we'll take it."
Before I could flash my friend a hello-didn't-you-see-he-was-aboutto-crack look, he quipped: "Dude, you were arguing over like, $1, man."
He was right, of course, but I didn't realise. All I saw was that this guy was charging me one-third above the market rate.
The next day, I was going to buy the same friend a drink at a cafe when he mentioned how expensive it was.
"Wow, 40 yuan," he said, referring to his watermelon juice. "That's close to $9."
He is right. It is double, even triple what you would pay in Singapore, but I had gotten so used to such prices in Beijing cafes that I didn't blink.
It was the same during my time in Malaysia two years ago, where the favourable exchange rate meant that I almost never bothered converting numbers in my head.
Like some yao kwee (hungry ghost), I used to pile up the plate of my favourite nasi campur (mixed rice) with beef rendang and sambal goreng because, you know, one Singapore dollar equalled 2.5 ringgit at that time.
But when I moved from Kuala Lumpur to London, I went from yao kwee to simply yao (hungry). During my first month in London, I spent an inordinate amount of time scrutinising prices in supermarkets.
How can a lousy supermarket sandwich and a Coke cost $6, I asked my protesting stomach.
It was only a few months later, after I realised that every lousy sandwich and a Coke costs $6 that I stopped converting numbers and also started thinking, hmm, that $15 duck rice seems pretty good value.
So you can see how I am sometimes as confused as my niece, who last month declared to our family that her "book" - a two-page composition written on cardboard paper - was worth $20.90. And promptly forced my brother to pay for it.
Actually, with prices around the world increasingly shaped by trade, tariffs and migration, absolute value is a disappearing notion.
Why should my gigantic badminton bag and my tiny box of granola both cost $10 in China? But they do. Should one of them be cheaper than the other? That depends on where you used to buy badminton bags and granola.
Everything is relative. In my world, it is relative to Singapore, until I remember that I'm living somewhere else, then everything becomes relative to that new place.
But in between there is plenty of confusion - but also clarity.
One thing I can say with some certainty, for instance, is that the hawker food prices in Singapore take some beating for a developed country.
I am back in town for a short break, and few things make me happier than the $3 bak chor mee near my house, topped with fragrant chilli, mushrooms and generous portions of meat.
I used to think it is cheap - and it is. But after living elsewhere, I now know it is also priceless.