Recursion Spreadsheet Instructions

Open the spreadsheet template. The number pattern is displayed vertically. It is only possible to enter in four cells, and you can move easily from one to the others using the TAB key.

The column graph displays the first ten numbers in the pattern.

Students will explore many starting numbers and different recursion rules. Starting numbers can be decimals or negatives. In the process they will discover:

• adding a number is the inverse of subtracting it (as above)
• adding or subtracting a zero creates no new numbers
• multiplying by zero reduces everything to zero
• multiplying by 2 (doubling) grows very rapidly
• multiplying by 10 gives the powers of ten, growing
• multiplying by 0.1 gives powers of ten, decaying
• adding a negative number has the same effect as subtracting a positive number of the same ‘size’
• subtracting a negative number has the same effect as adding a positive number of the same ‘size’
• multiplying by –1 alternates between positive and negative values
• and a whole lot more.