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Browse Elementary Place Value
Stars indicate particularly interesting answers or
good places to begin browsing.
Selected answers to common questions:
Place value questions.
Rounding numbers.
Scientific notation.
Significant figures/digits.
 Significant Digits and Irrational Numbers [09/24/2005]

How can you determine the signifigant digits of a nonterminating or
irrational number like pi?
 Significant Digits and Zero [05/19/1999]

When are zeros significant and when are they not significant?
 Significant Digits in Measurement [08/13/2001]

I understand that there are rules to determine the significant digits in
measurement, but aren't all digits significant, especially zeros for
place value?
 Significant Digits in Numbers Written in Scientific Notation [06/20/2005]

A discussion between Dr. Peterson and a student who is struggling with how to determine significant digits in general and with regard to numbers in scientific notation in particular.
 Significant Figures [02/25/1999]

Why does 62.3 * 5.7 = 360 and not 355?
 Significant Figures in 36 2/3 [11/06/2001]

How many significant figures are there in the area "36 2/3 Acres"?
 Smallest 5Digit Number [02/05/2002]

My dad says the smallest 5digit number is 00000, but my teacher says it
is 10000. The dictionary says that zero is a digit. What's the right
answer?
 Square Numbers End in 0 1 4 5 6 9 [10/15/2002]

Why do all square numbers end in 0 1 4 5 6 9?
 Subtracting and Borrowing in a Column [09/05/2002]

A student borrowed in a column as follows: 6.9  7.92, to get 2.98.
Why won't borrowing work with this number?
 Subtracting Mixed Fractions With Borrowing [01/08/2004]

Two methods for subtracting mixed fractions involving borrowing
because the fraction being subtracted is larger than the other one.
For example, 5 3/8  10 6/8.
 Subtracting with Mixed Units [02/10/2009]

How would you subtract 1 ton, 12 lb, 6 oz from 4 tons?
 Truncating [01/19/2002]

What does truncating mean?
 Use and Meaning of 'And' in Naming Decimals [12/01/2004]

Can you please tell me what the word "and" means in the word form of a
decimal number?
 Using Hyphens to Indicate Place Value [08/30/2004]

What is the difference between "five hundred thousandths" and "five
hundredthousandths"?
 What is a Number Base? [04/19/2003]

The base eight number 7n3 is equal to the base 7 number 1n35.
What digit does n stand for?
 Why Multiplying by 10 Just Adds a Zero at the End [10/18/2005]

My 8year old is having trouble understanding why multiplying by 10
just adds a 0 to the end of the number. Do you have any thoughts on
how to explain it to her?
 Why the Decimal Point Moves when Multiplying by 10 [02/11/2005]

I am trying to explain why when you multiply a number by 10 you move
the decimal point over one place to the right, and one place to the
left when you divide by 10.
 Working in Base 7 [08/02/2007]

How do I add, subtract, multiply and divide in base 7?
 Working Up to Counting Up [09/25/2003]

My daughter wants to learn how to make change by counting up.
 Writing Decimals from Words [10/05/1998]

Given a decimal written in words, how do you turn it into a decimal? In
other words, how do you turn the words into numbers?
 Writing Numbers in Words [09/15/1997]

Write each number in words: 1) 73.78007 2) 2.900087 (3) 34.4939.
 Zeros after the Decimal Point [09/17/2001]

I have a group of students who just can't comprehend my explanation of
how 3.70 is equivalent to 3.7 or 3.700 or 3.7000.
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