Multiplication and division

There are 227 NRICH Mathematical resources connected to Multiplication and division
Funny Factorisation
problem

Funny Factorisation

Age
11 to 16
Challenge level
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Using the digits 1 to 9, the number 4396 can be written as the product of two numbers. Can you find the factors?
Factoring factorials
problem

Factoring factorials

Age
11 to 14
Challenge level
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Find the highest power of 11 that will divide into 1000! exactly.
ABC
problem

ABC

Age
7 to 11
Challenge level
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In the multiplication calculation, some of the digits have been replaced by letters and others by asterisks. Can you reconstruct the original multiplication?
Vedic Sutra - All from 9 and last from 10
problem

Vedic Sutra - All from 9 and last from 10

Age
14 to 16
Challenge level
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Vedic Sutra is one of many ancient Indian sutras which involves a cross subtraction method. Can you give a good explanation of WHY it works?
Two Many
problem

Two Many

Age
11 to 14
Challenge level
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What is the least square number which commences with six two's?
Ones Only
problem

Ones Only

Age
11 to 14
Challenge level
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Find the smallest whole number which, when mutiplied by 7, gives a product consisting entirely of ones.
Book Codes
problem

Book Codes

Age
7 to 11
Challenge level
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Look on the back of any modern book and you will find an ISBN code. Take this code and calculate this sum in the way shown. Can you see what the answers always have in common?
Times right
problem

Times right

Age
11 to 16
Challenge level
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Using the digits 1, 2, 3, 4, 5, 6, 7 and 8, mulitply a two two digit numbers are multiplied to give a four digit number, so that the expression is correct. How many different solutions can you find?
Sam's Quick Sum
problem

Sam's Quick Sum

Age
7 to 11
Challenge level
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What is the sum of all the three digit whole numbers?
As Easy as 1,2,3
problem

As Easy as 1,2,3

Age
11 to 14
Challenge level
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When I type a sequence of letters my calculator gives the product of all the numbers in the corresponding memories. What numbers should I store so that when I type 'ONE' it returns 1, and when I type 'TWO' it returns 2, and so on.