## Numeral Systems: Binary, Decimal & Hexadecimal

### Why?

In Singapore, mathematics syllabus for P1 (primary one) includes addition, subtraction, multiplication, and division. Students work with **decimal** numbers. Learning about other numeral systems than decimal, they will understand: how a numeral system work in general; why decimal is the default choice.

### How?

**Scope**: learning how binary (base 2), decimal (base 10) and hexadecimal (base 16) systems work starting from 0 to 26; then +5, +10, etc.

**Materials**: 1) A3 sized paper; 2) snap cubes: 3 colors for each student; 100 pieces per color.

**Increment by 1**: walking through the number increment procedure with students:

- add one piece to the rightmost ‘ones’ column of a number system;
- carry over if the total units exceed the current place value – start from the ‘ones’ column till to the right:
- snap the all the units of the current column in a straight line and now they form one unit in the preceding column;

**Add more than 1**: ask students to add 5 or 10 directly:

- Snap the cubes to be added and fill the largest place value first – for example, to add 5, one can simply put 4 into the ‘four’ column and 1 into the ‘ones’ column in the base 2 board;
Carry over if necessary from the right-most.

Learned on: Feb 14, 2019

Reference: Paul A.