This year's competition is now closed: thanks for playing!

We'll be announcing the winner of the iPad Air shortly. In the meantime, take a look at the answers below.

Did you manage to crack the code?
Did you manage to crack the code?

Lock 1

  • Avogadro's number (to 4 significant figures) is 6022 x 1020.
  • The sum of the atomic numbers of Sulphur, Tellurium, Tungsten, Argon, Terbium, Lanthanum and Neodymium is 342.
  • The charge on an electron (to 4 significant figures) is −1602 × 10-22 C.

Lock 1 combination = 6022 + 342 − 1602 = 4762

Lock 2

  • The coefficient of linear expansion of aluminium is 24 × 10-6 K-1. At 10 °C an aluminium rod is exactly 30 cm long. At 30°C the rod has increased in length by 144 µm.
  • A current of 0.8 A passes through a metal wire of resistance 90 ? for 1 minute. 3456 Joules of energy are released.
  • A 500 kg container is placed on a surface. The coefficient of static friction between the surfaces is 0.4 and g = 9.81 ms-2. The magnitude of the force required to start sliding the box is 1962 N.

Lock 2 combination = 144 + 3456 + 1962 = 5562