GET stuff to prepare for exam :

- For mental calculations: secret of mental calculation
- Math's shortcuts :

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**1. Tricks for numbers:**

1.Any prime number greater than 3 is in form of 6k+1 or 6k-1.

2.Any factorial greater than 4 is end with 0.

For Example::

4 | 24 |

5 | 120 |

6 | 720 |

7 | 5040 |

8 | 40320 |

3.Product of any 4 consecutive Natural number is always divisible by 24.

for example:

1*2*3*4=24

7*8*9*10=5040.(which is divisible by 24)

4.Any perfect square having last

**two digits equal**is only one no is possible that is:144
5 N is natural number when :

**(N*N*N)/6 same reminder can be obtain by (N)/6**

This trick will help you to solve many questions regarding

**reminder problems**.
example:

find the reminder of :

6859/6

here 6859= (19)^3

which means our answer will be same reminder as (19)/6