Pictures can be stored in a computer as a grid of numbers. Each number gives the colour of that small area or pixel. This is also the way digital images are stored and represented on a screen.

The Romans had the same idea when creating mosaics to decorate their floors. They created designs using lots of small coloured stones or pieces of glass cut into squares. They called them tesserae. In this one the tesserae are labelled with Roman Numerals but the key is in decimal. Recreate the mosaic using the key.

To solve the puzzle you need to know what Roman Numerals mean. The Romans used letters for numbers so they wrote

I for 1 
V for 5 
X for 10 
L for 50 
C for 100

The Romans added these basic symbols like we do coins to make numbers in between so VIII means 8 as in King Henry VIII. A very early system just used addition like this. Later they got more complicated including  the idea that a smaller symbol before a bigger one means subtract it rather than add, so for example IX stands for 9 as it means X – I whereas XI means 11 as it means 10 + 1. Similarly XC means 90 whereas CX means 110.

Download 

Either download and print the pdf version, or if you don’t have a printer or want to practice spreadsheet IT skills use the spreadsheet version.

• the puzzle sheet [pdf]
• The solution sheet [pdf]
• Puzzle in spreadsheet [xlsx]