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Listed under:  Mathematics  >  Number (Mathematics)  >  Number operations  >  Mental arithmetic
Video

Multiples of five

When is a times table useful? Watch this video to see an example of when knowing a five times table comes in handy. Can you think of another example where knowing the times table could be useful?

Video

MathXplosion, Ep 31: Heavy vs big

How would you measure and compare the weight of something? Learn why big things aren't necessarily heavy. All you need is something heavy and a lot of something light and you’ll be able to prove that weight is not the same as size.

Video

Numbers Count: Multiply two numbers to get twenty!

Did you know that 5 times 4 equals 20? Did you also know that there are other numbers you can multiply to get to 20? See if you can come up with at least two other numbers.

Online

reSolve: Multiplication - reSolve Bakery

This series of three lessons explores strategies for multi-digit multiplication. Students are presented with a range of problems in the context of a bakery producing arrays of cupcakes. The lessons aim to develop a range of strategies based on the associative and distributive properties of multiplication, moving students ...

Online

Introduction to binary

This sequence of lessons focuses on what a binary number is, what a decimal number is, why binary numbers are important in digital systems and how to read and understand a binary number.

Video

MathXplosion, Ep 40: Kaprekar's operation

Did you know that 6,174 is a very mysterious number? In 1949, the mathematician Dr Kaprekar from India devised a process now known as Kaprekar's operation. First, choose a four-digit number where the digits are all different. Then rearrange the digits to get the largest and smallest numbers these digits can make. Finally, ...

Interactive

The difference bar: go figure

This tutorial is suitable for use with a screen reader. It explains how to split up numbers in your head when finding the difference between two numbers such as 26 and 73. Work through sample questions and instructions explaining how to use linear partitioning techniques. Find the difference between pairs of numbers. Split ...

Interactive

The difference bar: generate easy subtractions

Learn how to split up numbers in your head. Use a linear partitioning tool to help find the difference between pairs of two-digit numbers such as 25 and 34. In these examples, the difference is always less than ten. Split the numbers into parts that are easy to work with, work out each part and then solve the original calculation.

Interactive

Divide it up: puppies

Use a dividing tool to make equal shares of biscuits and toys in a pet shop. For example, share 34 biscuits equally between 6 puppies. Predict how many items each puppy will get, or how many packets can be filled. Check your prediction. Decide what to do with any leftovers. Complete a sentence describing the number operations.

Interactive

What's the problem: nature: level 2

Star as a contestant in a quiz show! Select three worded mathematical problems, about nature, from two categories: 'plants' or 'animals'. Identify the correct answer for each step in the problem-solving process. Examine the suggestions made by the panel to help you. Collect a prize based on your score.

Interactive

Wishball challenge: hundreds

Challenge your understanding of place value in whole numbers up to 999. Receive a starting number, such as 328, and work towards turning it into a target number, such as 177, within 20 turns. Spin a random digit, choose its decimal place value and use the given operation (either addition or subtraction) on your starting ...

Interactive

The foul food maker: go figure

This tutorial is suitable for use with a screen reader. It explains how the use of simple words can describe the likelihood of everyday events. How likely is an event: certain, likely, equal chance, unlikely or certainly not? Answer some questions using these words and then build your own examples. Learn how to describe ...

Interactive

Divide it up: grouping tool

Use a dividing tool to make equal shares of stationery such as pens, pencils or crayons. Complete a sentence describing a number operation. For example, pack 24 crayons into packets of 5. Predict how many packets are needed and identify how many items are left over.

Interactive

Wishball challenge: tens

Challenge your understanding of place value in whole numbers up to 99. Receive a starting number, such as 86, and work towards turning it into a target number, such as 18, within 20 turns. Spin a random digit, choose its decimal place value and use the given operation (either addition or subtraction) on your starting number. ...

Interactive

The number partner: go figure

This tutorial is suitable for use with a screen reader. It explains strategies for breaking up numbers into pairs of smaller numbers, eg 15 = 11 + 4. Work through examples of whole number pairs and sample questions. Apply these principles to solve additions or subtractions.

Interactive

Wishball: hundreds

Test your understanding of place value with three-digit numbers. Start with a three-digit whole number such as 507. A spinner provides a randomly generated digit. Choose its place value and add it to (or subtract it from) your starting number. Work towards a given target number, say 539, using other digits. You can choose ...

Interactive

The take-away bar: go figure

This tutorial is suitable for use with a screen reader. It explains strategies for solving subtractions in your head such as 87-39. Work through sample questions and instructions explaining how to use linear partitioning techniques. Solve subtractions by breaking them up into parts that are easy to work with, work out each ...

Interactive

Playground percentages

Help a town planner to design two site plans for a school. Assign regions on a 10x10 grid for different uses such as a playground, canteen, car park or lawn. Calculate the percentage of the total site used for each region. Use a number line to display fractions and equivalent fractions.

Interactive

The divider: with or without remainders

Solve divisions such as 147/7 or 157/6 (some have remainders). Use a partitioning tool to help solve randomly generated divisions. Learn strategies to do complex arithmetic in your head. Split a division into parts that are easy to work with, use times tables, then solve the original calculation.

Interactive

The array

Use an array-building tool to help solve multiplications. Explore strategies to break up multiplications. Create and solve easy multiplications such as 9x3. Examine relationships between rows, columns and areas in arrays.