What it means
The square of nine is a spiral of numbers starting at 1 in the centre. Prices that sit on the same angle of the spiral are considered related. The quick arithmetic version: take the square root of a price, add 0.25 for each 90° of rotation (0.5 for 180°, 1 for 360°), then square the result.
From a low of 100: √100 = 10. 10.25² = 105.06 (90°), 10.5² = 110.25 (180°), 10.75² = 115.56 (270°), 11² = 121 (360°).
Why traders use it
Gann believed prices move in geometric relationships. Traders use the levels as potential support and resistance or targets, usually together with other tools.
Chart examples
Square-of-nine levels from a low of 100
How to identify it objectively
- 1Choose a significant high or low.
- 2Take its square root.
- 3Add (or subtract) 0.25 per 90° step and square again.
- 4Mark the levels and watch for reactions.
Bullish use
- 1From a major low, the 90° and 180° levels above are potential targets.
- 2A close above a level can turn it into support.
Bearish use
- 1From a major high, subtract 0.25 steps for levels below.
- 2Rejection at a level is watched for shorts.
What confirms it
- A level coincides with structure or a round number.
What invalidates it
- Price trades through levels with no reaction.
How a hypothetical setup is built
Entry
On a bullish reaction at the 90° level after a pullback.
Stop
Below the reaction low.
Target
The 180° level.
A hypothetical illustration of how the concept is turned into a plan, not a recommendation. Practise it on a paper account first.
Related concepts
Historical testing
Not tested on The Tradeskill. The levels are deterministic, so they are easy to test against random levels of the same spacing; do that before trusting them.
Limitations: when it fails
- The choice of starting price changes every level.
- Levels are close together at low prices and far apart at high prices.
- No reliable published evidence of an edge.
Knowledge check
Pick an answer to see the explanation. Nothing is saved.