What’s on the Floating Point poster
The rule, 3 worked examples, and the mistake everyone makes.
- Binary floating point cannot represent most decimal fractions exactly.
- 0.1 + 0.2 = 0.30000000000000004
- Why = 0.1 has no exact binary form
- Comparing = abs(a - b) < 1e-9
- Money = Store integer pence, or a decimal type
- Common mistake: Rounding at the end of a long float calculation → Using a decimal typ…
A 64-bit double has about 15–17 significant decimal digits. Beyond that, integers stop being exact too.
Questions about the Floating Point poster
- What’s on the Floating Point poster?
- The rule, 3 worked examples, and the mistake everyone makes. Binary floating point cannot represent most decimal fractions exactly.; 0.1 + 0.2 = 0.30000000000000004; Why = 0.1 has no exact binary form; Comparing = abs(a - b) < 1e-9; Money = Store integer pence, or a decimal type; Common mistake: Rounding at the end of a long float calculation → Using a decimal typ…. A 64-bit double has about 15–17 significant decimal digits. Beyond that, integers stop being exact too.
- Who is the Floating Point poster for?
- Floating Point belongs to the Computing section rather than to a school year, because computing is not something one grade owns. Anyone learning foundations can pin it up — a beginner, a student mid-course, or someone revising years later.
- When should you use the Floating Point poster?
- Never compare floats with ==. Never store money as a float. A wall chart earns its place by being glanceable from where the work is happening, so Floating Point belongs on the wall where that computing work actually happens, within glancing distance, rather than filed away.
- What other posters go with Floating Point?
- Big-O Complexity, Binary, Hex & Decimal and Bits, Bytes & Sizes sit alongside Floating Point in the Computing section. Printed together they make a wall rather than a single sheet, which is how a reference set actually gets used.Big-O ComplexityBinary, Hex & DecimalBits, Bytes & Sizes
- Is the Floating Point poster free to download and print?
- Yes. Floating Point downloads as a free PDF with no account, no email and no watermark, like everything else in the Computing section. Print as many copies as you like for a home, a classroom, a library or a tutoring group; reselling the file is the only thing the licence rules out.Read the licence
- What size does the Floating Point poster print at?
- Floating Point is a vector PDF laid out for US Letter, and prints on A4 with Fit to page — the same file, no separate download. Because every mark on it is drawn rather than photographed, it stays sharp enlarged to A3, A2 or A1 at a copy shop. Colour carries emphasis only, so a greyscale print of Floating Point loses nothing.Printing guide
Related posters
Charts that sit alongside Floating Point on the same wall.
Browse every Computing poster, or start from the full catalogue.