Mental arithmetic

Two Cuisenaire rods on a number line.
Select the Cuisenaire rods by clicking on the above buttons.

D1: Cuisenaire Rods with number lines.
Useful for lots of mental arithmetic activities (also work on fractions and ratio).
The on and off buttons.
Top: horizontal or vertical Cuisenaire rods.
Delete all the Cuisenaire rods, they can also be deleted individually by dragging to the bin.
Turn the numbers on or off.
Turn the grid on or off.
Turn the horizontal number line on or off. The number lines can be dragged up or down, or left or right.
Turn the vertical number line on or off.


D2: Find the difference between two numbers
Two numbers are shown on a number line. Drag the two numbers along the number line or click on 'change'.
Select the numbers on the number line by clicking on the appropriate button.
Coloured bars can be shown to indicate one way of working out the difference. Click on the button showing the coloured bars to hide or show them.
Click on the zoom button to zoom in or out. The number line can be dragged from side to side when it is magnified.
Click in the boxes to hide or show the numbers or difference.
D3: Find the total of two numbers
Same idea as above but shows the total of two numbers. 50 is the maximum size for each number. No zoom facility.

What are the hidden numbers?
Reveal a few numbers, the pupils have to identify some of the hidden ones.

D4: 100grid activities
This number grid can be used to identify hidden numbers. Click on a square to reveal the number. Useful for addition and subtraction activities using a normal 100grid or number sequence activities using a random grid.
There are four types of number grid:
1 to 100, 1 in the topleft hand corner, 100 in the bottomright.
100 to 1, 100 in the topleft hand corner, 1 in the bottomright.
A random grid starting with smallest number in the topleft.
A random grid starting with highest number in the topleft. 

Mental arithmetic 'tests' each comprising ten questions on addition, subtraction, multiplication, division, place value, sequences, fractions, measures, time and money.
D5: National Curriculum: level 3 'test 1'
D6: National Curriculum: level 3 'test 2' : slightly more difficult
A mental arithmetic 'test' comprising ten questions on addition and subtraction.
D7: National Curriculum: level 3

Hidden numbers and missing numbers

Click on the polygon person to reveal the hidden number, click again to hide it.
Use this button to hide or show the number line.
Click on the polygon person to reveal the hidden number, click again to hide it.

D10: Hidden numbers 1 Lots of different addition and subtraction sums with one of the numbers hidden. D10 to D15 are now all on the same Whiteboard Worksheet
Click on the options buttons to change the sums. The option buttons generate the following types of sum:
1. Add small numbers
2. Add numbers less than 30
3. Add numbers less than 50
4. Subtract small numbers
5. Subtract numbers less than 30
6. Subtract numbers less than 50
7. Add or subtract small numbers
8. Add or subtract numbers less than 50
9. Add or subtract a multiple of 10 to or from a twodigit number, without crossing 100
eg 63  30, 47 + 30
10. Add or subtract a pair of multiples of 100, without crossing 1000 (with number line)
eg 600  300, 400 + 500
11. Add a single digit to a 'teens' number, or subtract a single digit from a 'twenties' number, crossing 20
eg 17 + 5, 25  8
12. Find a small difference between a pair of numbers lying either side of 20, or another multiple of 10
eg 63  58, 37 + ? = 45
13. Add or subtract a multiple of 10 to and from a twodigit number, crossing 100
14. Add or subtract a pair of multiples of 100 crossing 1000
15. Add or subtract 100 to or from any threedigit number, without crossing 1000
16. Add or subtract a single digit to or from a twodigit number, crossing the tens boundary
eg 58 + 7
17. Find a small difference between a pair of numbers lying either side of a multiple of 100 from 100 to 1000
eg 607  598
18. Add or subtract any pair of twodigit numbers
D16: Hidden numbers 2 Lots of different addition and subtraction sums with one of the numbers hidden. D16 to D29 (except D23) are now all on the same Whiteboard Worksheet
Click on the options buttons to change the sums. The option buttons generate the following types of sum:
1. Add or subtract twodigit multiples of 10
2. Add or subtract a pair of multiples of 100, crossing 1000
eg 600 + 800
3. Add or subtract a multiple of 10 to or from a two or threedigit number, without crossing the hundres boundary
eg 672  50
4. Add a two or three digitnumber to a multiple of 10, 100 or 1000
eg 300 + 234
5. Find what to add to a two or threedigit number to make 100 or the next higher multiple of 100
eg 456 + ? =500
6. Find what to add to a fourdigit multiple of 100 to make the next higher multiple of 1000
eg 4100 + ? =5000
7. Add or subtract threedigit multiples of 10
eg 560 + 350
8. Add or subtract a singledigit multiple of 100 to or from a three or fourdigit number, crossing 1000
eg 600 + 567
9. Add or subtract a threedigit multiple of 10 to or from a threedigit number, without crossing the hundreds boundary
eg 540 + 324
10. Find what to add to a decimal with units and tenths to make the next higher whole number
5.6 + ? = 6
11. Add or subtract fourdigit multiples of 100
eg 3400  1800
12. Find what to add to a decimal with units, 10ths and 100ths to make the next higher whole number or 10th
eg 4.56 + ? = 4.6
D23: Add three 3digit multiples of 100
700 + + 500 = 1800

Random number generator: target board

A screenshot of the number generator.

D30: A flexible interactive whiteboard resource which generates 24 different sets of numbers. The resource will open in a new window.
Options include:
Random numbers to 100
Random numbers 25 to 25
Totals, eg 27 and 24 and 51(27 + 24 = 51)
Differences, eg 65 and 36 and 29 (65  36 = 29)
Number bonds to 10, eg 6.1 and 3.9
Number bonds to 100, eg 66 and 34
Select the type of numbers to be generated by clicking on the numbered buttons at the top.
1: random numbers to 100, 2: random numbers 25 to 25, 3: totals, 4: differences, 7: number bonds to 10, 8: number bonds to 100
The colour of the number can be changed. Select one of 8 colours then click on a number.
The numbers can be put arranged in a grid, click this button
or arranged randomly, click this button
The numbers can be grouped by dragging them about.
The numbers can be discarded by dragging them to the bin.
Children can use the resource to match pairs:
eg 3x5 and 15 (timestables 1)
eg 35 and 70 (doubles)
A clock starts when a set of numbers has been generated. The clock can be hidden or shown (click the green clock button). It can be stopped by clicking the 'stop the clock' button!
The clock can be used to see who can match the pairs in the quickest time.

Missing symbols: use the symbols >, < and =


Decide which symbol to use
D31: >, < and =

Solving problems

Solve puzzles and problems such as 

Missing number problemsolving activities
Sum, Difference and Product
D8: Two whole numbers D9: Two decimal numbers Two small numbers are generated, their sum, difference and product are worked out.
Hide the two numbers, can you work out what they are from their sum, product and difference?
Click on 'change' to generate two more numbers.
Hide the product, work out the two numbers from their sum and difference.
Hide the odd or even labels: is it possible to say whether a sum, product or difference will be odd or even?
Sum puzzle
Write a number in each circle so that the number in each square equals the sum of the two numbers on either side of it. There are many possible solutions for the square arithmagon. The answer sheet will give one set of solutions.
D36: Sum puzzle


Complete the magic squares
D37: 3 x 3 magic square D38: 3 x 3 magic square (more difficult)
D39: 4 x 4 magic square


Triangle puzzle
The three numbers on each side of the triangle must add up to the red target number.
D40: Triangle puzzle

