Digital Lights

Digital Lights

Originally calculators used seven small lights (or LEDs) to form the digits 0 to 9.

1. Which light is used most?

2. Which light is used least?

3. Which letters of the alphabet could be represented using this system?

4. How many different combinations of 'on' and 'off' can these seven lights make?

A Mathematics Lesson Starter Of The Day


Topics: Starter | Calculator | Investigations | Mixed

  • ijince, Guildford, England
  • I have just discovered this website and it looks very useful. When school starts again I will probably use the Starter of the day as my home page but I would also like to pick starters appopriate to a topic. A dilema as I might run into the same one twice! Also, I know it sounds lazy but are the answers available somewhere?
  • Transum,
  • Thanks for your comments. Most starters have the answers included at the bottom of the page for those who have a Transum subscription.
  • Mrs o'Hagan's 2nd yr class, Holyrood RC Sec, Glasgow
  • E. Top, top left,middle, bottom left and bottom! and we know there are lots more!!!
  • Mrs Hamilton,
  • Letters=A,B,C,D,E,F,G,H,J,L,O,P,S & U
  • Y7 Mr Heeley's Krew, Rawthorpe High, Huddersfield
  • We enjoyed this starter, it stimulated our great minds and "lighted" up our day!
    We have also recently got hooked on Fast Factors. Mr Heeley aka MC Protractor currently holds all the records. Try and beat me everybody - bring it on!!
    Keep it cushtie Transum xx
  • Priory School form 8r2, Shrewsbury
  • We found Y can be done too.
  • Mr Peters, Uplands Junior School
  • My year 4 top set made A B C D E F G H I J L N O P Q R S T U V Y and Z if you allow us a little imagination and some lower case letters
  • Kate Alliston And 6A, Tyrrells Primary School
  • My class made W and M by turning the calculator on its side! Still stuck on K and X though.
  • Mr Pouney, The Vyne Community School
  • My year 10s found :
    a b c d e f g h I j l n o p q r s t u y.
  • Beacon Community College, Crowborough, 7XMa2
  • The letters that cannot be represented K, M, X, V, W and T.
  • Ariane, Nelson
  • I found eleven of the letters that ARE DIFFERENT FROM DIGITS. A, C, E, F, G, H, J, L, P, U, and Y. Challenging problem, but we worked it out in the end
  • R Crimmins, TORC
  • Lower case b, c, d, e, g, h, I + j(without dot above), l, n, o, r, t, u, y
    Upper case A, B, C, D, E, F, H, I, L, O, P, S, U.

How did you use this starter? Can you suggest how teachers could present or develop this resource? Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for Maths teachers anywhere in the world.
Click here to enter your comments.

If you don't have the time to provide feedback we'd really appreciate it if you could give this page a score! We are constantly improving and adding to these starters so it would be really helpful to know which ones are most useful. Simply click on a button below:

Excellent, I would like to see more like this
Good, achieved the results I required
Didn't really capture the interest of the students
Not for me! I wouldn't use this type of activity.

This starter has scored a mean of 3.0 out of 5 based on 35 votes.

Previous Day | This starter is for 23 October | Next Day



1. The lower right light is 'on' for 9 of the digits 0-9

2. The lower left light is only 'on' for 4 of the digits 0-9

3. Here's a start:

A could be represented with all lights on except for the bottom light;

B could be all lights on (same as the digit 8);

C could be top, upper left, lower left and bottom;

(If anyone manages to complete this list please share your answers here)

4. There are 27 or 128 different combinations.


Your access to the majority of the Transum resources continues to be free but you can help support the continued growth of the website by doing your Amazon shopping using the links on this page. Below is an Amazon search box and some items chosen and recommended by Transum Mathematics to get you started.

Have you read Craig's book yet?

Craig Barton must surely be the voice of Mathematics teachers in the UK. His wonderful podcasts interviewing the industry experts have culminated in this wonderful book. As Craig says: "I genuinely believe I have never taught mathematics better, and my students have never learned more. I just wish I had known all of this twelve years ago..." more...

"How I wish I’d taught maths' is an extraordinary and important book. Part guide to research, part memoir, part survival handbook, it’s a wonderfully accessible guide to the latest research on teaching mathematics, presented in a disarmingly honest and readable way. I know of no other book that presents as much usable research evidence on the dos and don’ts of mathematics teaching in such a clear and practical way. No matter how long you have been doing it, if you teach mathematics—from primary school to university—this book is for you." Dylan Wiliam, Emeritus Professor of Educational Assessment, UCL.

The Craig Barton Book

Graphic Display Calculator

This handheld device and companion software are designed to generate opportunities for classroom exploration and to promote greater understanding of core concepts in the mathematics and science classroom. TI-Nspire technology has been developed through sound classroom research which shows that "linked multiple representation are crucial in development of conceptual understanding and it is feasible only through use of a technology such as TI-Nspire, which provides simultaneous, dynamically linked representations of graphs, equations, data, and verbal explanations, such that a change in one representation is immediately reflected in the others.

For the young people in your life it is a great investment. Bought as a gift for a special occasion but useful for many years to come as the young person turns into an A-level candidate then works their way through university. more...

iPad Air

The analytics show that more and more people are accessing Transum Mathematics via an iPad as it is so portable and responsive. The iPad has so many other uses in addition to solving Transum's puzzles and challenges and it would make an excellent gift for anyone.

You have to hold iPad Air to believe it. It’s just 7.5 millimeters thin and weighs just one pound. The stunning Retina display sits inside thinner bezels, so all you see is your content. And an incredible amount of power lies inside the sleek enclosure. So you can do so much more. With so much less. more...

Before giving an iPad as a gift you could add a link to iPad Maths to the home screen.

Click the images above to see all the details of these items and to buy them online.

Online Maths Shop

Laptops In Lessons

Teacher, do your students have access to computers?
Do they have iPads or Laptops in Lessons?

Whether your students each have a TabletPC, a Surface or a Mac, this activity lends itself to eLearning (Engaged Learning).

Laptops In Lessons

Here a concise URL for a version of this page without the comments.

Here is the URL which will take them to a related student activity.




©1997-2018 WWW.TRANSUM.ORG