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Factorial Fun
Objectives
To be able to follow instructions and record observations accurately.
Resources
Abacus 4 Textbook 3 | 6 counters | Squared paper
Today's Lesson
Main Activity
As the mental warm ups for each day, ask your student to count back in 20s, 25s, or 50s. Be sure to cross 100 barriers and start from random numbers.
For example:
‘Count back in 50s from 356’.
Turn to page 55 in Abacus 4 Textbook 3.
Read the instructions about placing and arranging the counters.
Have fun with your student investigating the different ways you can do this.
Once you have completed the exercise with the three counters, ask your student to follow the investigation with up to 6 counters, filling in the chart as they go.
Your student may be interested to know that sequences of numbers like this have a mathematical description, e.g. ‘4 x 3 x 2 x 1’ is known as ‘4 factorial’ and can be abbreviated to 4!.. Thus, 2! = 2, 3! = 6, 4! = 24 and so on.