Multiplication and division

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Getting the balance right

In this article for primary teachers, Ems shares some common misconceptions surrounding the equals sign, and suggests ways to help learners develop their understanding.
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Mathdoku demonstration

This video of Charlie and Liz solving a 6 by 6 Mathdoku may give you ideas for strategies to try.
problem
Double digit

Age

11 to 14

Challenge level

Choose two digits and arrange them to make two double-digit numbers. Now add your double-digit numbers. Now add your single digit numbers. Divide your double-digit answer by your single-digit answer. Try lots of examples. What happens? Can you explain it?
problem
As easy as 1,2,3

Age

11 to 14

Challenge level

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.
problem
Two many

Age

11 to 14

Challenge level

What is the least square number which commences with six two's?
problem
Largest number

Age

11 to 14

Challenge level

What is the largest number you can make using the three digits 2, 3 and 4 in any way you like, using any operations you like? You can only use each digit once.
problem
Why 8?

Age

11 to 14

Challenge level

Choose any four consecutive even numbers. Multiply the two middle numbers together. Multiply the first and last numbers. Now subtract your second answer from the first. Try it with your own numbers. Why is the answer always 8?
problem
Machines

Age

7 to 11

Challenge level

What is happening at each box in these machines?
problem
Interstellar

Age

11 to 14

Challenge level

What number could replace * so that */5 is between 3 and 4?
problem
Integrated product Sudoku

Age

11 to 16

Challenge level

This Sudoku puzzle can be solved with the help of small clue-numbers on the border lines between pairs of neighbouring squares of the grid.