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Useful Mathematics Tricks:
Division, Multiplication and more
Division
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A number will be divisible by 3 if
the sum of all the digits is a multiple of 3. For example,
35,431,452 is
divisible by 3 as 3 + 5 + 4 + 3 + 1 + 4 + 5 + 2 = 27 and
27 is divisible by 3.
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A number will be divisible by 4 if
its last two digits is divisible by 4. For example,
4,349,898,548 is divisible by 4 as the last two digits is 48 and 48
is divisible by 4 (Note: if the last 2 digits are 00, the number is
divisible by 4 as it is a multiple of 100 and 100 is divisible by
4).
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A number will be divisible by 9 if
the sum of all the digits is a multiple of 9. For example,
53,438,652 is divisible by 9 as 5 + 3 + 4 + 3 + 8 + 6 + 5 + 2 = 36
and 36 is divisible by 9.
Multiplication
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To calculate the square of a 2-digit number ending in 5,
simply multiply the first digit by the next consecutive number and
put 25 as the last two digits. For example, 25 x 25 = (2x3)25
= 625, 35 x 35 = (3x4)25 = 1225.
Prime Number Table
Below is the table of the
first 30 prime numbers.
You can print them out to assist your children to
memorize them.
Print this table
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2 |
3 |
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5 |
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7 |
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11 |
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13 |
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17 |
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19 |
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23 |
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29 |
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31 |
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37 |
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41 |
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43 |
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47 |
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53 |
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59 |
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61 |
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67 |
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71 |
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73 |
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79 |
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83 |
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89 |
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97 |
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101 |
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103 |
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107 |
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109 |
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113 |
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Multiplication Table
Below are two multiplication tables,
one in words and one in numbers. You can print them out to assist
your children to memorize them.
Print this table
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Two-One Two |
Three-One Three |
Four-One Four |
Five-One Five |
Six-One Six |
Seven-One Seven |
Eight-One Eight |
Nine-One Nine |
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Two-Two Four |
Three-Two Six |
Four-Two Eight |
Five-Two Ten |
Six-Two Twelve |
Seven-Two Fourteen |
Eight-Two Sixteen |
Nine-Two Eighteen |
| Two-Three Six |
Three-Three Nine |
Four-Three Twelve |
Five-Three Fifteen |
Six-Three Eighteen |
Seven-Three Twenty One |
Eight-Three Twenty Four |
Nine-Three Twenty Seven |
| Two-Four Eight |
Three-Four Twelve |
Four-Four Sixteen |
Five-Four Twenty |
Six-Four Twenty Four |
Seven-Four Twenty Eight |
Eight-Four Thirty Two |
Nine-Four Thirty Six |
| Two-Five Ten |
Three-Five Fifteen |
Four-Five Twenty |
Five-Five Twenty Five |
Six-Five Thirty |
Seven-Five Thirty Five |
Eight-Five Forty |
Nine-Five Forty Five |
| Two-Six Twelve |
Three-Six Eighteen |
Four-Six Twenty Four |
Five-Six Thirty |
Six-Six Thirty Six |
Seven-Six Forty Two |
Eight-Six Forty Eight |
Nine-Six Fifty Four |
| Two-Seven Fourteen |
Three-Seven Twenty One |
Four-Seven Twenty Eight |
Five-Seven Thirty Five |
Six-Seven Forty Two |
Seven-Seven Forty Nine |
Eight-Seven Fifty Six |
Nine-Seven Sixty Three |
| Two-Eight Sixteen |
Three-Eight Twenty Four |
Four-Eight Thirty Two |
Five-Eight Forty |
Six-Eight Forty Eight |
Seven-Eight Fifty Six |
Eight-Eight Sixty Four |
Nine-Eight Seventy Two |
| Two-Nine Eighteen |
Three-Nine Twenty Seven |
Four-Nine Thirty Six |
Five-Nine Forty Five |
Six-Nine Fifty Four |
Seven-Nine Sixty Three |
Eight-Nine Seventy Two |
Nine-Nine Eighty One |
| Two-Ten Twenty |
Three-Ten Thirty |
Four-Ten Forty |
Five-Ten Fifty |
Six-Ten Sixty |
Seven-Ten Seventy |
Eight-Ten Eighty |
Nine-Ten Ninety |
Print this table
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2x1 = 2 |
3x1 = 3 |
4x1 = 4 |
5x1 = 5 |
6x1 = 6 |
7x1 = 7 |
8x1 = 8 |
9x1 = 9 |
| 2x2 = 4 |
3x2 = 6 |
4x2 = 8 |
5x2 = 10 |
6x2 = 12 |
7x2 = 14 |
8x2 = 16 |
9x2 = 18 |
| 2x3 = 6 |
3x3 = 9 |
4x3 = 12 |
5x3 = 15 |
6x3 = 18 |
7x3 = 21 |
8x3 = 24 |
9x3 = 27 |
| 2x4 = 8 |
3x4 = 12 |
4x4 = 16 |
5x4 = 20 |
6x4 = 24 |
7x4 = 28 |
8x4 = 32 |
9x4 = 36 |
| 2x5 = 10 |
3x5 = 15 |
4x5 = 20 |
5x5 = 25 |
6x5 = 30 |
7x5 = 35 |
8x5 = 40 |
9x5 = 45 |
| 2x6 = 12 |
3x6 = 18 |
4x6 = 24 |
5x6 = 30 |
6x6 = 36 |
7x6 = 42 |
8x6 = 48 |
9x6 = 54 |
| 2x7 = 14 |
3x7 = 21 |
4x7 = 28 |
5x7 = 35 |
6x7 = 42 |
7x7 = 49 |
8x7 = 56 |
9x7 = 63 |
| 2x8 = 16 |
3x8 = 24 |
4x8 = 32 |
5x8 = 40 |
6x8 = 48 |
7x8 = 56 |
8x8 = 64 |
9x8 = 72 |
| 2x9 = 18 |
3x9 = 27 |
4x9 = 36 |
5x9 = 45 |
6x9 = 54 |
7x9 = 63 |
8x9 = 72 |
9x9 = 81 |
| 2x10 = 20 |
3x10 = 30 |
4x10 = 40 |
5x10 = 50 |
6x10 = 60 |
7x10 = 70 |
8x10 = 80 |
9x10 = 90 |
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