## Trace Tables

A trace table shows the value of each variable at each step of an algorithm. The algorithm below calculates monthly simple interest on a principle P over a period of years T. It then calculates a monthly allowance which spend the result over a year.

1 Input P

2 Input R

3 Input T

4 Let I = (P * R * T)/100

5 Let A = P + I

6 Let M = A/(12 * T)

7 Print M

8Stop

The variables are the principal P, the simple interest rate R and the time period T. The trace table shows one column for each variable.

Line | P | R | T | I | A | M |

1 | 500 | |||||

2 | 500 | 6 | ||||

3 | 500 | 6 | 4 | |||

4 | 500 | 6 | 4 | 120 | ||

5 | 500 | 6 | 4 | 120 | 620 | |

6 | 500 | 6 | 4 | 120 | 620 | 51.67 |

7 | 500 | 6 | 4 | 120 | 620 | 51.67 |

8 | 500 | 6 | 4 | 120 | 620 | 51.67 |