Could you help me understand how it is mathematically incorrect? If 2-ten one is 21, why would 2-ten zero be 200?

Hello Ashlee,

You have raised an excellent question and you are correct, it is not mathematically incorrect, but it is redundant. She need not have the extra zero.

When I called it mathematically incorrect, I was thinking of how the young children who are learning this way will write the place value 234 as 200304, and it takes some time, and practice using the place value cards to get them to write 234. I pictured having to teach the child this concept and having to teach them that 2ten is 20, not 2ten zero, which many would write as 200, just like at first they write 2ten 1 as 201, and then we correct them with the place value cards and the use of the abacus to show them that 2ten 1 is written as 21. That is what I was picturing.

Thank you for asking, please let me know if you have any more questions. You can email me directly at Carissa@alabacus.com .

Thank you for giving your child a RightStart in Math,

Carissa
RightStart™ Mathematics by Activities for Learning, Inc.

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Please let me know if you have any more questions. You can email me directly at Carissa@alabacus.com .