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.
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This starter has scored a mean of 3.1 out of 5 based on 132 votes.

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

Here is an interactive version of a digital display. Click the lights to turn them on or off.



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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.

Student Activity



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