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Elementary Archive

Browse Elementary Subtraction
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Selected answers to common questions:
    Flashcards/worksheets on the Web.
    Order of operations.
    Number sentences.
    Subtraction with borrowing/regrouping.

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How Much did the Tree Grow? [11/07/2001]

A white pine was 16 m tall in 1962. It was 20 m tall in 1965. It is now 34 m tall. How much has it grown since 1962?

Incorrect Application of PEMDAS and Order of Operations [09/14/2006]

My students think PEMDAS means that all addition should be done before any subtraction is done. How can I show and convince them that they need to do both operations at the same time working from left to right?

Interpreting the Difference Between Two Numbers [09/22/2006]

If a question asks "What is the difference between 15 and 12" or "What is the difference between 12 and 15," would your responses be +3 and -3 respectively? Or would they both be +3?

Invented Strategies for Subtraction [09/18/2002]

I need some help understanding two students' ways of understanding math.

Is Subtraction Separation or Taking Away? [01/24/2002]

Do we introduce subtraction as 1) separation of a group into two parts and we know one part and are trying to find the other, or 2) taking away?

Left Associativity [05/27/1999]

Is the 'left to right' rule in mathematics a law or is it just used for consistency?

Lining Up Decimal Points [03/03/2003]

Why do we line up decimal points for addition and subtraction but not for division and multiplication?

Mental Math: Making Tens [09/16/2003]

What is the 'make a ten' strategy in mental math?

The Missing Million [06/12/2001]

If I have six million dollars and my friend has three million dollars, I am wealthier than my friend by three million dollars...

Multiple Subtraction by Missing Addend Method [09/26/2002]

To get the difference by the missing addend method we are not supposed to change the given problem into subtraction of one subtrahend, but to work out the problem as it is. We are not even to use regrouping.

Multiplier, Sum, Difference, Product, Quotient, Dividend [11/25/1997]

What is a multiplier? an addend? a minuend? a product? Why is the number that is being divided the "dividend"?

Negative 5 and Minus 5 [10/05/2002]

Can you tell me the difference between negative five and minus five?

Negative Number or Subtraction? [12/16/2003]

When I see a '-' in front of a number, how can I tell whether it's supposed to indicate a negative number, or a subtraction?

Order of Numbers in Subtraction and Division [11/09/1999]

Why can you add or multiply numbers in any order, but you cannot switch order when you divide or subtract?

Order of Operations [01/25/1998]

Evaluate the expression: 30 - 5^2 + 4^3.

Order of Operations: Parentheses as Packages [10/25/2001]

I need help figuring out the steps in this expression: 5-{-4[2^4-11(-9- 1)]}=

Order of Operations vs. Associative Property [10/10/2002]

Is the associative property an exception to the order of operations, a corollary, or something totally unrelated?

Order of Operations vs. Distributive Property [02/04/2005]

Does the distributive property contradict the rules of order of operations? When we have a(b + c) order of operations says we should add first in the parentheses, then multiply, but the distributive property says we can multiply first to get ab + ac, then add.

Parts of a Subtraction Problem [04/09/2001]

What are the numbers 4 and 1 called in the subtraction 4 - 1 = 3?

Properties of Subtraction [04/08/1997]

Is subtraction commutative? associative?

Puzzle with a Difference [03/19/2003]

Place each number from 1 through 10 in a box. Each box must contain a number that is the difference of two boxes above it, if there are two above it.

Regrouping and Subtracting [03/29/2001]

37-9: Do you need to regroup? Subtract the ones. Subtract the tens. How many are left?

Regrouping Four 10's [10/15/2001]

How would you regroup four 10's to find the difference between 341 and 228?

Rules for Subtracting Integers [10/31/2001]

I need to write rules for subtracting integers. Where can I get this information?

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 a Negative from a Positive [04/11/2006]

How can I explain subtracting a negative number from a positive, like 10 - (-6) = 16, to my 5th grade students?

Subtracting a Negative Number [08/16/1999]

Can you explain how subtracting a negative number is the same as adding a positive number?

Subtracting Big Numbers [11/20/1995]

What's 245715 - 105065 ?

Subtracting Big Numbers [02/27/1998]

How do you do problems like 678-564 and 455646546475-67574657?

Subtracting Decimals [09/16/1997]

I don't know how to subtract decimals.

Subtracting Fractions with Borrowing [12/17/2002]

When you are subtracting a fraction, do you always take one away from the whole 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 Mixed Numbers [01/23/1998]

I don't really understand subtracting mixed numbers.

Subtracting Mixed Numbers By Counting On [06/01/1998]

How do you find what to add to 1 and 3 fourths to get 4 and 5 twelfths?

Subtracting Mixed Numbers with Borrowing [03/31/2009]

A question on how to subtract 6 1/8 - 3 1/3 leads to examples of borrowing and regrouping in various contexts, including time, money, liquid volume, and of course mixed numbers. An alternative approach of producing an equivalent but easier problem is also presented.

Subtracting Negative Integers [09/12/2001]

I have questions like: -3 - -13. My teacher said to do it in a money way....

Subtracting Negative Numbers [05/11/1998]

Can you explain how to subtract a negative number from a positive number and a positive number from a negative number?

Subtracting Negative Numbers [12/06/2005]

We learned the rule that to subtract negative numbers you change to addition and switch the sign on the number, so that -9 - (-3) becomes -9 + (3). I want to know why we do that, not just that we have to do it.

Subtracting Time [02/27/2001]

A marathon runner crossed the finish line after running for 2 hours, 48 minutes, and 12 seconds. She crossed the line at 9:18:12 A.M. When did the marathon start?

Subtracting with Mixed Units [02/10/2009]

How would you subtract 1 ton, 12 lb, 6 oz from 4 tons?

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