Doubling and Halving

Doubling a number means adding it to itself, or multiplying by 2. So double 3 is 6, double 6 is 12, and double 12 is 24. The number gets bigger very fast.

Pick a starting number with the slider. Then press to double it again and again. Watch how a small number like 2 grows to 4, 8, 16, 32 in just a few steps.

If a recipe for 2 people uses 1 cup of rice, doubling gives 2 cups for 4 people. If your pocket money doubles, you can buy twice as many sweets. Halving is the opposite trick.

If you fold a paper in half just 10 times, the thickness doubles each fold and becomes very thick. This is why doubling is called exponential growth: small starts can grow huge surprisingly fast.