## More adding three 2-digit numbers mentally

I have had a number of requests for more on adding three 2-digit numbers mentally, so, here is another page. There are a number of different techniques which can be used when adding these and it certainly would not be the best way to proceed to just add them in the order they appear. Looking for pairs that make 30, doubling of teens, adjusting by 1 or 2 are just some of the skills needed to answer these quickly and accurately.

Also, don’t forget that correct answers are better than fast incorrect answers, so it is always a good idea to check by adding them in a different order.

Add 3 2-digit numbers practice (2)

This page can be found in the year 5 Calculating category, but many more addition pages can also be found in the four rules section.

## Resource of the week: scalene triangles

This week we take another look at types of triangle. A lot of work is done on triangles in Primary Schools and by year 5 and 6 most children are familiar with the properties of right angled triangles, equilateral triangles and isosceles triangles. An equilateral triangle has all three sides equal and all three angles equal; an isosceles triangle has two equal sides and two equal angles. However, fewer children know about the scalene triangle. A scalene triangle is one which has no sides the same length and no equal angles. Right angled triangles could also be scalene if all the sides are different lengths.

Thanks to MathSphere Ltd for this worksheet: and there are many more similar pages, both on their site and part of the ‘It’s All Figured Out’ CD.

Go to our year 5 shape resources

## Year 5 addition of three 2-digit numbers

Here is a practice page of adding three 2-digit numbers mentally. This is a really good test of how well children can use their skills and knowledge as there are several different approaches/techniques that can be used.

These skills  include:

1. Because addition can be done in any order it is often easier to start with the largest number.

2. Knowing pairs of teen numbers (e.g. knowing 17 + 17 is 34) will help with a question such as 17 + 15 + 17.

3. Looking for pairs that make a multiple of 10: (e.g. 17 + 13 = 30)

4. Adding the tens before the units and then counting on.

This page can be found in our Year 5 category but there are also a great collection in our Four Rules category.

## Resource of the week: year 5 square numbers

This is just one of a short series of square number maths worksheets for Year 5.  It is an interesting and worthwhile exercise asking children to see if they can make a square out of 10 or 12 smaller squares (not overlapping etc) using plastic or card squares. Rectangles are possible, but not squares.

They can then be asked to find which numbers can be made into a square. This can be done either with smaller squares or as dots in an array.

There are several ways that questions involving square numbers can be phrased, including:

What is 4 squared?

What is the square of 4?

What number multiplied by itself makes 16?

Square numbers 2

## Maths worksheet: the triple jump

The Triple Jump is a fascinating event, combining great athleticism with co-ordination. Originally known as the hop, step and jump it is an excellent activity to carry out with children using a standing start rather than a run up. The American, James Connolly was one of the early competitors, winning in Athens in 1896.

Triple jumpers take off on the ‘hop’ stage and land on the same foot. They then take one step onto the other foot before a final jump, landing with two feet into the sand. The rules concerning the landing are the same as for the long jump with the nearest mark to the board being the distance measured.

The distances jumped really are amazing and it is well worth marking out on a field exactly how far they jump. For example our greatest triple jumper, Jonathan Edwards holds the World Record with a jump of 18 metres and 29 centimetres.

The worksheet looks at some of the greatest ever winners of the Triple Jump as well as completing a graph showing the distances jumped and would be best suited to upper primary children and can be found in our Year 5 Handling Data section.

Triple jump men

## Year 5 Maths Challenge: the very best 2-digit answers

This is quite an intriguing worksheet as it is difficult to decide if there is a best possible answer. In fact, part of the challenge could be to decide what the criteria are for deciding what counts as the best possible answer.

The idea is to use each of the digits 0 to 9 just once each to fulfil the statements below. So, for example 98 could be used for the largest even number and 67 used as the largest odd number. But is this the best option? Would 86 and 97 be better?

One which does have to be considered early on is the multiple of five as this ensures either the digit 5 or the digit 0 are used.

A good worksheet to generate discussion and with no answer it is entirely up to you!

This page can be found in the Year 5 Using and Applying Maths category.

## Resource of the Week: decimal fractions

Some children have difficulty realising that the same numbers can be written in different ways, especially when dealing with decimals and decimal fractions. This page is a good test of understanding, probably most suited for year 5 children (/10 yrs old).

0.23 can be read as 23 hundredths or 2 tenths and 3 hundredths. As a fraction it would be written as 23/100.

With a number such as four and three hundredths it is important to keep the zero in the tenths so that it is written as 4.03.

Watch out for a common mistake on a question such as thirteen hundredths when children write 0.013; the one digit has been placed in the hundredths column when it should be in the tenths with the 3 digit in the hundredths.

Decimal fractions: hundredths (pg 1)

## Year 5 maths worksheet: multiplication

Here is the second in a mini-series of maths worksheets that look at using knowledge of multiplication and tables to complete number sentences.

Again, the most important aspect of this page is to illicit what processes children use to answer the questions, and it is a worthwhile experience to ask yourself exactly how you went about it in your mind to reach the answer – it is not necessarily the way we would explain to children, yet it could well be a very effective way. Let’s look at a couple of the questions;

Question 3: ? x 4 = 44.

This I can answer without doing any kind of calculation in my head because I know, off by heart, that 4 x 11 = 44.

Question 7: ? x 5 = 110

A harder question which can be tackled several ways. I actually worked from knowing that 20 fives make 100 and then adding two more fives for the ten, making the answer 22. I probably wouldn’t suggest this to children. What I would suggest is double the 110 to make 220 and then divide by ten to make 22 (and explaining why this method works).

Complete multiplication number sentences (2)

## Year 5 subtraction: missing digits

Last week I published a page of addition with missing digits. This proved very popular and I have had several requests for something similar for subtraction; so here it is.

The calculations have been laid out in the tradition, standard method of written subtraction, except that two of the digits are missing. It is not as easy as it looks to find the missing digits, especially with a question such as:

41? – 2?9 = 207

In this question the units have to be adjusted, which will have a knock on effect in the tens. This page should only be given to children who have quite a good grasp of the standard written method of subtraction, but beware, it is harder than it looks!

Subtraction: missing digits

## Year 5 addition: missing digits

On the face of it this might look like an easy page, but in fact many children find this quite tricky. It should not be tried until children have a good grasp of the standard written method of addition.The addition calculation has been laid out in the standard way, together with the answer. However, two of the digits in the sum are missing. Sometimes it is easy to find the missing digit, but not always, especially when tens have been ‘carried’ into hundreds.

If children get this page correct it shows a good understanding of the standard method of addition. If they struggle it would be well worth looking again at this method.