Multiplying by a power of 2

To multiply a number by 2, 4, 8, 16, 32, or some other power of 2 just keep doubling

the product as many times as necessary. If you want to multiply by 16 then double the

number 4 times since 16 = 2×2x2×2.

15×16: 15×2 = 30. 30×2 = 60. 60×2 = 120. 120×2 = 240.23×8: 23×2 = 46. 46×2 = 92.

92×2 = 184.54×8: 54×2 = 108. 108×2 = 216. 216×2 = 432.

Practice these tricks and you’ll get good at solving many different kinds of arithmetic

problems in your head, or at least quickly on paper. Half the fun is identifying which

trick to use. Sometimes more than one trick will apply and you’ll get to choose which

one is easiest for a particular problem.

Multiplication can be a great sport! Enjoy.