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Listed under:  Mathematics  >  Number (Mathematics)  >  Number operations  >  Associativity
Video

MathXplosion, Ep 2: Double that number

Explore an age-old multiplication method that repeatedly doubles numbers to get a product. Learn how this ancient method of multiplication is similar to that used by modern computers.

Video

MathXplosion, Ep 11: Fun facts about the number seven

Did you know that the digits on opposite faces of dice will always add up to seven? Use dice as fun tools to reinforce fact families of seven, multiples of seven and subtraction skills.

Video

MathXplosion, Ep 1: Magic 9s

Follow these simple calculations to illustrate the special properties of the number 9. Pick your favourite number between 1 and 9 and multiply that number by 3. Add 3 to your answer. Multiply the result by 3. Treat your two-digit answer as two separate numbers and add them together. No matter what number you pick to start ...

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 multiplier: go figure

This tutorial is suitable for use with a screen reader. It explains strategies for solving complex multiplications in your head such as 22x38. Work through sample questions and instructions explaining how to use partitioning techniques. Solve multiplications by breaking them up into parts that are easy to work with, use ...

Image

Chinese abacus, c1900

This is a rectangular wooden abacus (15.5 cm x 29 cm x 2.5 cm), made in about 1900. It has two decks (divided horizontally by the beam) of 13 rods inserted vertically in the frame. On the bottom deck there are five wooden beads on each rod and on the top deck there are two beads on each rod. The abacus has a removable wooden ...

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

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 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

Wishball challenge: whole numbers

Test your understanding of decimal place value with whole numbers. Receive a starting number, such as 3786, and work towards turning it into a target number, 7664. Spin a random digit, choose its decimal place value and use the given operation (either addition or subtraction) on your starting number. Be careful not to overshoot ...

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

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

Wishball: whole numbers

Test your understanding of decimal place value with whole numbers. Receive a starting number, such as 3786, and work towards turning it into a target number, such as 7664. Spin a random digit, choose its decimal place value and decide whether to add or subtract the random digit from your starting number. You can use a 'Wishball' ...