Skip to content
ENExplore Calculators

Doubles And Halves Calculator

Work out doubles and halves instantly with clear inputs, formula shown and shareable results.

About Doubles And Halves Calculator

Doubling multiplies by two and halving divides by two; repeating either k times multiplies or divides by 2 to the power k. Doubling and halving is the fastest mental route to the 4, 8 and 16 times tables, and repeated doubling is a first taste of exponential growth.

Formulas

Double and half

double = number x 2; half = number / 2

Repeated doubling

after k doublings = number x 2^k; after k halvings = number / 2^k

Worked example

With the default values below, Doubles And Halves Calculator returns Double of 72.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Number
36
Double this many timesaccepts 1–20
3

Results

Double
72.000
Half
18.000
Doubled repeatedly
288.000
Halved repeatedly
4.500000

Step by step

  1. 1Values used
  2. 2Double and half
  3. 3Repeated doubling
  4. 4Double= 72.000
  5. 5Half= 18.000
  6. 6Doubled repeatedly= 288.000
  7. 7Halved repeatedly= 4.500000

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 6 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Doubles And Halves figure worked out?

double = number x 2; half = number / 2. Doubling multiplies by two and halving divides by two; repeating either k times multiplies or divides by 2 to the power k.

Why does this matter?

Doubling and halving is the fastest mental route to the 4, 8 and 16 times tables, and repeated doubling is a first taste of exponential growth.

What do I need to enter?

Enter number, double this many times. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.

Related Calculators

Doubles And Halves Calculator – Calculate Double & Half