The Blindfolded Challenges

In October 2025, I was invited to Shanghai by Qing Ting for three "impossible" feats of the mind — all blindfolded. Looking back, it was less a demonstration of skill and more a rollercoaster of nerves, and a very unexpected plot twist.

Challenge 1: Blindfolded Cubing

I self-taught blindfolded cubing a month ago using the Old Pochmann method, and had only performed it once in front of others. By October, I'd upgraded to M2 for edge pieces. My success rate sat comfortably above 80%, and each solve typically took me 5–8 minutes total. As long as I could focus, this would be fine.

Challenge 2: Recitation of 500 Digits of Pi

This one? Easy. In June 2022, I broke Singapore's national record in pi memorisation with 2,626 digits. Five hundred digits is a warm-up. I practised once the day before flying to Shanghai and called it done.

Challenge 3: Blindfolded Mental Calculation — 6 Digits × 6 Digits

Now this was the hard one. I hadn't even considered it until the Principal of Qing Ting casually suggested I try — ten days before the challenges. My entire résumé in mental calculation was winning first place at my town's competition… in first grade.

I quickly learned the criss-cross method and spent nine days attempting 6×6 multiplication blindfolded. For nine days, I failed every single attempt. It wasn't until I was on the train to Shanghai that I had a "Eureka!" moment: I could fuse the criss-cross method with my Peg system. I got my first correct answer the night before the event.

What Actually Happened

The Reality Check: When Things Go Sideways

After lunch, we started with blindfolded cubing. I made a strategic decision: let my student go first. She had learned blindfolded cubing in just two weeks — impressive — but the noise in the venue rattled her so badly she forgot the last move. So I stepped up.

Normally, I spend 2–4 minutes memorising and 3–5 minutes solving, depending on how scrambled the cube is. But the organisers handed me their cube — a non-magnetic one — and the room was full of people chatting. I couldn't lock in. Memorisation dragged. And on my first attempt, the unfamiliar cube tripped me up. I failed.

Second attempt. This time I deliberately spent longer memorising, making sure every piece was locked in. During the solve, I slowed down, double-checking each algorithm before executing it. When I thought I'd finished all my moves, something felt off. I didn't remove the blindfold. I sat there, calmed myself, retraced my steps — and realised I'd skipped two algorithms. I went back, corrected the moves, and pulled off the blindfold.

The "Easy" Task Almost Breaks Me

Next: pi. Since I thought this was the easy one, I blindfolded myself and rattled off 500 digits in about three minutes. Except — I made careless mistakes. Twice. Two attempts burned on sloppy pronunciation of digits I could recite in my sleep.

One chance left.

On the final attempt, I slowed down and listened to every syllable leaving my mouth. All 500 digits, correct.

The Grand Finale: 15 Minutes of Mental Gymnastics

Last up: the blindfolded mental calculation. Two six-digit numbers appeared on the screen. I had 30 seconds to memorise them — but I only needed a few. The timer started the moment the numbers disappeared.

Here's how the criss-cross method works for 6×6 multiplication: you generate eleven intermediate values (each two or three digits), then add their hundreds and tens forward through the chain to produce each digit of the final answer. To keep all of this in my head, I paired the criss-cross with my peg system and a memory palace — encoding each intermediate result as an image, placed along a mental route.

After the carry-overs, the final answer was a 12-digit number. I arrived at it in about 8 minutes, then spent the remaining time double-checking. When the 15 minutes were up, I wrote my answer on the paper.

It was wrong. Or so they said.

I sat there trying to find where I'd gone wrong — and couldn't. Then came the twist: their answer key was the one with the error. My result was correct. I got it right on my first attempt.

The Moral of the Story

I went from a "National Record Holder" failing at 500 digits to getting the hardest math of my life right on the first try against a broken answer key.