Examples of Incorrect Answers
How the Mistakes are Made
Misconception Explained
In this math misconception, when the sum of two tens digits exceeds 10, the value of the resulting hundred digit is improperly combined with the sum of the single digits. When the sum of two single digits exceeds 10, the value resulting tens digit is not combined with the sum of the tens digits, instead, it is holding the ten’s digit by itself and pushing the value of the ten’s digit from the sum of two ten’s digits to the hundred’s place. This “carrying to the right” error seems to be a mismemory of which direction the carrying should go, but conceptually, such error results from not understanding the place value of numbers.
Concepts Invovled
- Place Value
Discussion Questions
Example
Questions to Ask
- What does the 7 in 76 mean? (seven tens)
- What does the 6 in 76 mean? (six singles)
- What does the 4 in48 mean? (four tens)
- What does the 8 in 48 mean? (eight singles)
- When we add 76 and 48, how many singles are we adding? (6 and 8)
- What’s the sum of 6+8? (14)
- What does that 1 mean in the sum 14? (one ten)
- What does that 4 mean in the sum 14? (four singles)
- When we add 76 and 48, how many tens are we adding? (7 and 4)
- What’s the sum of 7 tens and 4 tens? (11 tens)
- How much is ten tens equal to? (100)
- How should we write 11 tens? (110)
- How many hundred and how many ten are in 110? (one hundred and one ten)
- Other than that one hundred, how many tens are there altogether now? (two tens: one ten from 7+4 tens and one ten from 6+8)
- How should we write 1 hundrend, 2 tens, and 4 singles? (124)
