SXN-150 is ¥165, SXE3-3000 is ¥3,300 — Mitsubishi Pencil's catalogue numbers can be read as prices. Half of them, anyway

Catalogue numbers are usually a run of digits that tells you nothing. Mitsubishi Pencil is a partial exception: the digits are sometimes the price.

Of the 24 Mitsubishi Pencil models in PencilDB, eleven carry a number. We checked each one against its current list price.

Six of them: the number is the pre-tax price

In all six, multiplying the digits by 1.1 lands exactly on the list price. The number is the price before Japan's 10% consumption tax, and the shelf price includes it.

The other five do not match

Sometimes the number has become part of the product's name. The 307 in Signo 307 is what people call the pen; it is not a price.

Some miss by only a little

What is interesting is how differently they miss. Signo 307 and Style Fit are far off. But the New 3-Colour (558 against ¥550) and the Advance (615 against ¥605) are out by about ten yen.

Two paths lead there. Either the number was never a price, or it matched at launch and was left behind by a price rise.

PencilDB's data cannot tell you which. A catalogue number is fixed when the pen is launched; list prices are revised. We can see that the two have drifted apart, but the number does not record why.

Prefix is the line, middle is the width, tail is the colour

The rest of the number is more straightforward.

The prefix marks the line. M3 and M5 are mechanical pencils, and the digit is the lead diameter (0.3mm, 0.5mm). SXN is single-colour Jetstream, SXE3 the three-colour, MSXE5 the 4&1 multi-pen. UM and UMN are Uni-ball.

After the hyphen comes the ball diameter: Jetstream Standard shows 05, 07 and 38. That line is made in 0.38mm, 0.5mm, 0.7mm and 1.0mm.

And everything after the final dot is the barrel colour. Kuru Toga Standard has 155 catalogue numbers in PencilDB, and most of them are the same pen in another colour, with only that tail changing.