Golden Numbers are the most sought-after serial numbers in Singapore’s currency—they’re like the brightest stars in the world of banknote collecting. These 25 special numbers are chosen by the Monetary Authority of Singapore (MAS) before any new banknote prefix is released, and are auctioned off as a complete set.

Before 2004, the Golden Numbers comprised:

• The first 10 serial numbers: 000001 to 000010

• The 9 solid numbers: 111111 to 999999

• Four prosperity numbers: 000088, 000888, 008888, and 088888

• The ascending laddered number: 123456

• And the millionth note: 1000000, which was the only banknote with a seven-digit serial number.

In 2004, things changed slightly. After MAS took over from BCCS, the 1000000 serial number was removed from the Golden Number set. New printing technology meant they no longer had to produce exactly one million notes per prefix. If a note had a printing defect, it was simply skipped—there was no longer a need to replace it just to reach the 1000000 mark. Instead, MAS added another prefix to make up the quantity.

To replace the missing millionth number, MAS added a new one: 654321, a neat descending pattern. From then on, 999999 became the highest serial number in a prefix. As a result, banknotes with the 1000000 serial number became increasingly rare—and much more valuable to collectors.