Stage: 3 and 4 Challenge Level: 
Make a line of zeros ( about 10 ).
Put zero in B2 and press Enter.
Then click and drag the bottom right-hand corner to the
right.The contents of the cell (zero) will be replicated as far
as you drag.
Click on B3 and type the formula:
= A2 + C2
This formula creates a sum using the two cells immediately
above, left and right.
Press Enter, then click and drag the bottom right-hand corner
as before. The whole row now has that kind of formula.
Highlight the row and, again using the bottom right-hand
corner, drag down for about five rows.
What you now have is an array of connected values.
The first row is all set to zero, and all the cells in the rows
below contain a formula which creates a sum using the two cells
immediately above it, left and right.
Go to a middle cell in the first row and change the value to a
1. Press Enter and check the effect.
Finally go to the Tools drop down menu and choose Options.
Check you have the View tab selected, you will see the option
to not show zero values.
Click OK and a triangular array will present itself.
Experimental probability. Tree diagrams. Probability distributions, expectation and variance. Mathematical modelling. Theoretical probability. Conditional probability. Summation of series. Approximate solution by numerical methods.. Random variables. Spreadsheets.
Published January 2003.
Copyright © 2007. University of Cambridge. All rights reserved.
NRICH is part of the family of activities in the Millennium Mathematics Project, which also includes the Plus and Motivate sites.
email: nrich@damtp.cam.ac.uk
