Google followers quickly solved the maths clue hidden in its secondary offering of shares on Thursday. Now they have to figure out the bigger mystery of what it will do with the $4bn it plans to raise.

The idiosyncratic internet company, which loves to set challenging and quirky intelligence tests to job aspirants, announced almost a year to the day after its initial public offering that it would be issuing an additional 14,159,265 shares. Add a leading 3 and the numbers are the same as 3.14159265, or Pi - the ratio of the circumference to the diameter of a circle.