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.
- Associative, Distributive Properties [9/5/1996]
Please explain the associative and distributive properties.
- Basic Real Number Properties [07/31/1997]
I need information about basic real number properties: associative,
commutative, closure, identity, inverse, distributive.
- Cross-Multiplication [08/04/2002]
Can you explain cross-multiplication?
- Distributive Property, Illustrated [09/28/2001]
How can I show (12*2) + (12*3) using the distributive property?
- Finger Multiplication for the 9s [06/10/1998]
Do you have any tricks for learning the times table for 9?
- Help With Multiplication and Percents [11/11/1996]
Can you help me with multiplication so that I can better understand
- Homeschooling Multiplication [7/7/1996]
My son can't seem to memorize his times tables and therefore can't
- Lattice Multiplication [8/30/1996]
Can you please explain the lattice method of multiplication?
- Lattice Multiplication Explained [10/20/1999]
Can you explain why the lattice method of multiplication works?
- Learning Only 36 of the Times Tables [11/04/2001]
My mother says that I only need to know 36 of the times tables because
problems can be reversed to a higher problem. What are the 36 problems?
- Least Common Multiple Puzzle [03/24/2003]
What is the smallest number divisible by 1,2,3,4,5,6,8,9,10 that is
- Manipulating Positive and Negative Numbers [8/9/1996]
Could you explain the rules for adding, subtracting, multiplying, and
dividing positive and negative numbers?
- Memorizing Multiplication Facts [02/25/2001]
I can't remember my multiplication facts. I have flash cards, but they
- Memorizing Multiplication Tables [01/06/1997]
I am having a problem memorizing my times tables. How can I do this
- Multiples and Factors [06/02/2003]
What is the difference between multiples and factors?
- Multiples of 9 Number Puzzle [03/23/2003]
If you take a two-digit number, add the digits, and subtract the sum
from the original number, why is the answer always a multiple of 9?
- Multiplication's Multiple Meanings: Unified by the Distributive [01/01/2015]
Area? Matrix multiplication? Scaling and rotation? A parent seeks a global
understanding — or at least some internal consistency — as to what ties
together all the operations called "multiplication." Building up from the natural
numbers, where multiplication is repeated addition (MIRA), Doctor Peterson teases out two
- Multiplying by 0 [03/09/2001]
Why, when multiplying any number by 0, do you get 0?
- Multiplying by 9, Step by Step [11/05/2001]
I need help with 9 x 240,531.
- Multiplying Two 2-Digit Numbers [03/25/1997]
How do you do 28 x 24?
- Odd and Even Multiplication [02/17/1999]
Is it true that multiplying an even number and an odd or even number
always gives an even number?
- Order of Operations for Solving Equations [10/12/1995]
How would you multiply a question like this: -2(x-y)^2 ?
- Order Of Operations in Four Steps [02/15/1998]
I need help figuring out what operation to do first.
- Prime Numbers [01/31/1997]
What are the prime numbers and why are they prime numbers?
- Properties of Real Numbers [05/20/1997]
What are the associative, the commutative, and the zero product
- Reciprocals [12/19/1996]
What is the use of reciprocals?
- Rectangles and Factors [09/09/1998]
How many rectangles can you make with 10 small squares? 5 small squares?
12 small squares?
- Remembering Multiplication Tables [2/5/1996]
Is there an easy way to remember multiplication tables?
- Running Laps and LCMs [02/11/1999]
Bill, Bob, and John run 1/3rd, 1/5th, and 1/6th of a lap per minute,
respectively. How many laps do they need to run to cross the finish line
at the same time?
- Russian Peasant Method of Multiplication [10/07/1998]
I understand the 'Russian peasant' method of multiplication, but not why
- Russian Peasant Multiplication [02/26/2001]
Can you explain why the Russian Peasant algorithm works? How do the
numbers added relate to the multiplier and multiplicand?
- Tips for Learning Multiplication Tables [08/13/1998]
I have great difficulty with my 4, 6, 7, 8, and 9 times tables...
- Using Parentheses [11/16/1998]
Can you explain how to use parentheses to tell the order of operations?
- What is 4/5 x 10? [2/10/1995]
What is the answer to this fraction? Please explain.
- What is an exponent? [8/8/1996]
Can you explain what an exponent is?
- Working with Integers [01/12/1999]
Could you explain how to divide, multiply, add, and subtract integers?
- 3/4 of _____ Is 90 in Three Ways [03/24/2010]
In a multiplication problem like "Three-quarters of _____ is ninety," how do you fill-in-
the-blank with the factor that satisfies the equality? Doctor Ian presents three different
methods: guess-and-improve; the equivalency between multiplication and division;
and multiplying through by a reciprocal.
- Adding a Zero When Multiplying a Decimal [06/21/2001]
I don't understand why you add a zero when multiplying decimals.
- Adding Tax and Tip [07/19/1998]
In pricing our hotel luncheons, we charge a base price plus a 6.8% tax
and a 20% service charge. How would I find the total in one step?
- Additive Identity and Other Properties [01/03/1999]
Can you explain the identity of zero and the commutative and
multiplicative properties? Why are they special?