Search Results For “adding and subtracting”

Applying knowledge to add and subtract decimals mentally.

Add twenty and take one is much quicker than trying to add nineteen. But not always!

Use the numbers in the octagon to create and answer subtraction questions using multiples of 10 and decimals.

Doubling 2-digit numbers and halving 3-digit numbers mentally.

Some people like to start doubling with the units, others like to start with the tens. It doesn?t matter as long as the method is fast and accurate.

When we are multiplying by a number ending in 5 we can double the number and halve the other number before multiplying (by a multiple of ten, making it easy).

Remember to move the digits two places to the right to divide by 100.

We return to an important concept again: the relationship between multiplication and division.

Understanding and using factors of numbers can make mental multiplication easier.

What happens when a number is multiplied or divided by 10, 100 or 1 000?

Tips and hints on using a calculator, including negative numbers and recurring decimals.

Looking at the properties of cuboids, prisms and pyramids.