## Want to keep learning?

This content is taken from the Davidson Institute of Science Education at the Weizmann Institute of Science's online course, Maths Puzzles: Cryptarithms, Symbologies and Secret Codes. Join the course to learn more.
1.5

## Davidson Institute of Science Education at the Weizmann Institute of Science # A few preliminaries

Just before we start, it would be a good idea that we all ‘speak’ the same math notation language and refresh our minds with some basic math.

For addition, we will be using the short and long addition formats with the usual ‘+’ sign.

For subtraction, we will be using long subtraction formats with the usual ‘-‘ sign.

For multiplication, we will be using short and long multiplication formats with the usual ‘X’ sign.

For division, we will be using short and long division formats. Division can be denoted either using two dots ‘:’, or two dots with a horizontal line between them (this is the usual standard) ‘÷’.

It will also be useful to remember that every whole number has factors - numbers that divide the given number without leaving a remainder. For example: The factors of the number 10 are 1, 2, 5 and 10. All these numbers divide 10 without a remainder. The factors of the number 5 are 1 and 5 because only 1 and 5 divide the number 5 without a remainder. A number that has only two factors is a Prime number - it divides only itself and the number 1. Here is a fun explanation about factors and an online ‘factor calculator’.