Summary
Contents
The author focuses especially on weaknesses in numeracy often observed in adults, and in teacher-trainees in particular.
Check-up 12: The Commutative Laws
Check-up 12: The Commutative Laws
This check-up and the following two are designed to make explicit some fundamental laws of arithmetic. Whatever the numbers a and b,
- is it always true, sometimes true, or never true that a + b = b + a?
- is it always true, sometimes true, or never true that a − b = b − a?
- is it always true, sometimes true, or never true that ab = ba?
- is it always true, sometimes true, or never true that a ÷ b = b ÷ a?
Discussion and Explanation of Check-up 12
The statements in (a) and (c) are known as the commutative laws of addition ...