 Back to Subtract
|
Answer to Logo Question
 |
The logo for decomposition illustrates the principle of renaming. The logo shows that one ten is equal to 10 ones. When using decomposition in subtraction, the ten is renamed as 10 ones so that it can be added to the ones. |
 |
The logo for equal addition illustrates that when the same amount is added to the subtrahend and the minuend the difference between the two numbers remains the same. For example to subtract 25 from 43, we add 10 to both numbers (we add ten ones to 43 and one ten to 25). This allows the formal algorithm to be completed without changing the difference between the two numbers. |
Back to Teaching algorithms for subtraction