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 TOPICS This page:   multiplication    Search   Dr. Math See also the Dr. Math FAQ:   multiplication facts and   order of operations Internet Library:   multiplication T2T FAQ:   learning to multiply ELEMENTARY Arithmetic    addition    subtraction    multiplication    division    fractions/decimals Definitions Geometry    2-dimensional      circles      triangles/polygons    3D and higher      polyhedra Golden Ratio/ Fibonacci Sequence History/Biography Measurement    calendars/      dates/time    temperature    terms/units Number Sense/ About Numbers    infinity    large numbers    place value    prime numbers    square roots Projects Puzzles Word Problems 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.     Number sentences.     Order of operations. Multiplying a Number by Zero [09/14/2001] When any number is multiplied by zero, why is the result zero? Multiplying Billions [12/17/1997] How do you multiply 50 billion by 55 septillion? Multiplying by 1 [09/01/1998] Why doesn't a number change when you multiply it by 1? Multiplying by 1000 [03/10/1997] What is 2,542 times 1,000? Multiplying by 11 [09/16/1997] We said: 568 x 11 and after about 5 seconds she said the answer was 6248. How did she do it so quickly? Multiplying by a Decimal [11/10/1994] How come when you multipy 0.36 and 88 you get 9.4270, which is less than what it should be? Multiplying by Nine [01/10/1997] Why is the sum of the two digits 9 when you multiply 9 times any number between 1 and 10? Multiplying by Zero [03/01/2002] Why does any number times zero equal zero? Multiplying Decimal Numbers and Placing the Decimal Point [09/20/2007] Why does counting up the total decimal places when multiplying decimal numbers work? Multiplying Decimals and Decreasing Answers [12/02/1998] Why does multiplying by a decimal decrease the answer? How can you have less than what you started with when you multiply? Multiplying Fractions [01/20/1997] If multiplication is defined as repeated addition, why is the product of two fractions smaller than either of the fractions? Multiplying Fractions ... Made of Decimals? [06/16/2015] A student encounters multiplication homework with decimals in the numerator and denominator of a fraction. Showing equivalent expressions each step of the way, Doctor Ian lifts the veil separating decimals, fractions, and division. Multiplying Huge Numbers [5/9/1996] 8541 * 4372 = 37340252 - How can I check my answer? Multiplying Mixed Numbers [06/02/2003] Can you multiply mixed numbers without changing them into improper fractions? Multiplying Mixed Numbers [04/06/2004] Why do you need to convert mixed numbers to improper fractions before multiplying them together? What is the mathematical reason behind this operation? Multiplying Negative Integers [11/07/2001] Multiplying negative integers by breaking each negative number into a positive number multiplied by -1. Multiplying Negatives [1/13/1995] An adult ponders his elementary school lessons of multiplication and negative numbers. We can rewrite -2*3 as -2 + -2 + -2, but how can we re- write -2 * -3? Multiplying Sets [11/28/1994] If you are multiplying three sets of 8 do you write the problem 3x8 or 8x8? Multiplying Small Numbers [6/15/1996] I don't know what 6 times 6 is. Multiplying Two-Digit Numbers [06/04/1998] Can you show me how to multiply two-digit numbers like 39 x 98? Napier's Bones [01/20/1997] How do you use Napier's Bones to do multiplication? Napier's Rods [03/05/1999] How do Napier's bones work? Negative Two Kids [09/27/2002] Let's say 3 x 2 = 6. Three is how many kids there are in a 'group.' Two is how many 'groups' there are, and six is the answer. Now let's say 3 x (-2) = -6. How can you have negative two 'groups' of three kids? Number of Places in Products of Decimals [09/19/2002] When you multiply decimals, why is there always the same number of decimal places in the answer as in the problem? Number Properties [01/26/1998] What are the definitions for addition and multiplication of: closure, commutative, associative, and identity? Number Puzzle Based on Multiplication Ideas [08/07/2005] Find the smallest possible natural number that ends in 6 such that if the 6 is erased and placed in front of the remaining digits, the resulting number is 4 times as large as the original number. Numbers Bigger Than 12 [03/22/1997] How do you do problems like 14 x 7? One Billion as Product of Two Numbers with No Zeros [12/12/2001] Write 1,000,000,000 as the product of two numbers, neither of which contains any zeros. Ordering the Operations [11/10/1998] Why does the order of operations have to be in that order? Who set that specific order of operations? Order of Digits in Multiplication [03/27/2001] Why do we learn to multiply starting with the least significant digits in the ones place, instead of starting with the larger place values? Order of Operations [01/25/1998] Evaluate the expression: 30 - 5^2 + 4^3. Order of Operations [8/21/1996] How do I solve (8.2 - 3.6)(3 * 3.6 + 6)? Order of Operations and Fractions [02/22/2002] Given a+3 and b+5, is 105 / ab 7 or 175? 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. Paperless Multiplication [07/23/2002] How can I do two-digit multiplications (e.g., 99*98) without having to use paper? Parts of a Subtraction Problem [04/09/2001] What are the numbers 4 and 1 called in the subtraction 4 - 1 = 3? Properties, Defined and Illustrated [10/10/2001] I need a page of information on the commutative, associative, and F.O.I.L. properties. Proving That (-1) * (-1) = 1 [01/30/2006] At the high school level it is difficult to prove that -1 x -1 = 1. Is there a published proof somewhere that is appropriate for kids that age? Page: []

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