Computers count with just two digits, 1 and 0 — on and off. In Year 4 the row of light bulbs grows to five and then six, so coders can make every number up to 63.
What your child will learn
- Know the bulb values 32, 16, 8, 4, 2 and 1
- Read a binary number by adding the values of the bulbs that are on
- Choose which bulbs to switch on to make a number
- Write a number as a row of 1s and 0s
Each bulb is double the last
From the right, the bulbs are worth 1, 2, 4, 8, 16 and 32. Each new bulb doubles how high you can count: five bulbs reach 31, six reach 63.
Making a number
Start with the biggest bulb that fits. To make 22: 16 fits, leaving 6. 8 is too big. 4 fits, leaving 2. 2 fits, leaving 0. So 22 is 16 + 4 + 2, written 10110.
Example questions
Here are a few questions like the ones in the first quest. Can you solve them?
1. Each bulb that is on is worth 16, 8, 4, 2, 1 from left to right. What number do the bulbs show?
- 2
- 28
- 3
- 4
Show answer
Answer: 3. The bulbs that are on are worth 2 + 1 = 3. Bulbs that are off count for nothing.
2. Each bulb that is on is worth 16, 8, 4, 2, 1 from left to right. What number do the bulbs show?
- 10
- 21
- 11
- 2
Show answer
Answer: 10. The bulbs that are on are worth 8 + 2 = 10. Bulbs that are off count for nothing.
3. Each bulb that is on is worth 16, 8, 4, 2, 1 from left to right. What number do the bulbs show?
- 13
- 12
- 2
- 19
Show answer
Answer: 12. The bulbs that are on are worth 8 + 4 = 12. Bulbs that are off count for nothing.
Tips for grown-ups
- Use five coins: heads is 1, tails is 0. Make each other’s ages in binary.
- Count from 0 to 31 on one hand, with each finger as a bulb.
- Ask “what is the biggest number six bulbs can make?” and add them up.