See also the
Dr. Math FAQ:
order of operations
learning to multiply
3D and higher
Browse Elementary Multiplication
Stars indicate particularly interesting answers or
good places to begin browsing.
Selected answers to common questions:
Flashcards/worksheets on the Web.
Learning to multiply.
Least common multiple, Greatest common factor.
Order of operations.
- How Can Division Result in an Increase? [10/29/2003]
How is it possible for division to give you a larger number, instead
of a smaller one?
- How Does This Multiplication Method Work? [11/12/2003]
I've just learned a new way to multiply, where all you have to do is
double, split in half, and add. Why does this work? Could you extend
this to division, where all you have to do is double, halve, and add?
- How Many Border Stamps? [04/17/2001]
How many stamps are on the border of a 10x10 sheet of 100 stamps?
- How to Learn the Multiplication Table [09/01/2005]
Dr. Achilles, who struggled with the multiplication table as a kid,
relates some handy rules to help any student learn the table without
relying on rote memorization. It's a long article, but potentially
helpful to people struggling to learn or remember their multiplication
- Identity Element [10/12/2001]
What is an "identity element"?
- 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?
- Is the 2 Related to the Numbers in Parentheses? [10/05/2001]
Order of operations: Which is the correct way to solve this problem:
36/2(8-5) = ? What's a comparable English sentence?
- Large Arithmetic Problem [6/2/1995]
What is 784756895786 * 37846738654765485 + 547847358743 ?
- Lattice Method of Subtraction? [06/13/2006]
I've learned about the lattice method of addition and multiplication.
Is there a lattice method of subtraction?
- Learning Addition and Multiplication with Algebra [3/16/1996]
How do you know what the (a) is in algebra? I saw this on a picture:
a(1/a) = 1/a(a) = 1...
- Learning the Times Tables [10/12/2008]
I have a hard time with the times tables, and so I don't enjoy math.
Is there an easy way to get better at them?
- Learning Times Tables [12/06/2005]
I'm having trouble learning my times tables. Can you give me any help?
- Learning to Multiply and Divide Quickly [9/28/1995]
Do you have any ideas how I can learn to multiply and divide faster?
- Learning to Multiply Three-Digit Numbers [07/03/1998]
I would like to learn how to do multiplication of bigger numbers, like
120 x 743.
- Least Common Multiple [09/29/2001]
What is the least common multiple of 11, 13, and 17?
- Least Common Multiple with Zero [03/26/2003]
I'm trying to find any reference about the least common multiple of
two numbers when one (or both) is zero.
- Lengths in Pictures [4/5/1996]
A picture of an insect is k times the actual size. If the leg on the
picture is 3cm long, how long is the leg on the actual insect?
- Lining Up Decimal Points [03/03/2003]
Why do we line up decimal points for addition and subtraction but not
for division and multiplication?
- Macintosh Elementary Math Software [01/14/1997]
Internet resources and information for multiplication/computation.
- Massive Multiplication! [11/2/1994]
A first-grader wants to know if Dr. Math is good at multiplication.
- Meaning of Multiplying Fractions [12/09/1999]
What does it mean to multiply a fraction by a fraction?
- The Meaning of Powers, such as Squares and Cubes [3/14/1996]
What does the power mean? Like 5 to the power of 2?
- Memorizing Multiplication Tables [2/26/1996]
I'm a 3rd grade teacher and my lesson is on 6x7, 6x8, and 7x8 in
multiplication. I only know a trick for memorizing 7x8. Do you have any
suggestions for 6x7, 6x8 and others?
- Mental Math [07/25/2003]
I would like to find a trick for multiplying by 3367.
- Multiples [11/08/2001]
What is the most common multiple of 13 and 7? I have no clue what they
are even talking about.
- Multiples of Four [03/01/1999]
Is zero a multiple of four?
- Multiplicand, Multiplier [07/05/2001]
Do you agree with me that in the following mathematical sentence: 456x10,
456 is called the multiplicand and 10 is called the multiplier?
- Multiplication [02/11/1999]
How many decimal places should the product of 3.26 and 0.25 contain?
- Multiplication Before Addition [5/31/1996]
1000 * 20000 + 34 - 4023 = ?
- Multiplication Facts [02/12/2002]
Can you use the same multiplication fact to find 4x50 and 5x40? What is a
- Multiplication Makes It ... Smaller?! [07/21/2012]
The counterintuitively small products of some multiplication problems really bug a
student. By writing out and sketching a pattern, Doctor Peterson re-presents
multiplication — as scaling, and as an operation undone by division.
- Multiplication of Fractions [03/22/1999]
What are cancellations?
- Multiplication Signs [10/07/2002]
Why are there different ways to indicate multiplication?
- Multiplication Tables on the Web [11/24/1996]
Can you tell me where I can find the multiplication tables on the WWW?
- Multiplication Trick [02/08/1998]
When I multiply 25x25 I can do the answer in my head by multiplying the
first digit times the next highest number and then writing 25. Why does
- 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"?
- Multiply: 16 x 200 [12/6/1994]
I want to know the answer to the problem sixteen times two hundred.
- Multiplying 3+9 [11/15/1994]
A well-nested problem.
- Multiplying a 3-digit Number by a 2-digit Number [10/10/1995]
What is 697x56?
- Multiplying and Dividing Negatives [07/20/1998]
Can you explain multiplication and division with signed numbers? For
example what is the sign when you multiply negative numbers?