# Maths Tips and Tricks 6

## ഗണിത സൂത്രവാക്യം

ആദ്യത്തെ \'n\' എണ്ണൽ സംഖ്യകളുടെ തുക = n(n+1) /2.
ആദ്യത്തെ \'n\' ഒറ്റ സംഖ്യകളുടെ തുക = n².
ആദ്യത്തെ \'n\' ഇരട്ട സംഖ്യകളുടെ തുക = n(n+1).
ആദ്യത്തെ \'n\' എണ്ണൽ സംഖ്യകളുടെ വർഗ്ഗങ്ങളുടെ തുക = n(n+1)(2n+1) / 6.
ആദ്യത്തെ \'n\' എണ്ണൽ സംഖ്യകളുടെ ക്യൂബുകളുടെ തുക = [n(n+1)/ 2]².
ആദ്യ പദം \'a\', പൊതു വ്യത്യാസം \'d\' ആയാൽ n-മത്തെ പദം കാണാൻ = a+ (n -1) d.
ആദ്യ പദം \'a\', പൊതു വ്യത്യാസം \'d\' ആയാൽ, n പദങ്ങളുടെ തുക കാണാൻ = n/2[2a + (n - 1)d].
ആദ്യ പദവും (t1), n

## Trick to remember the name of G-8 Countries.

Code: ABC FIR GJ.

A : America .

B : Britain.

F : France.

I : Italy.

R : Russia.

G : Germany.

J : Japan.

## BODMAS Rule

BODMAS is an acronym and it stands for Bracket, Of, Division, Multiplication, Addition and Subtraction. .

This explains the order of operations to solve an expression. According to Bodmas rule, if an expression contains brackets ((), {}, []) we have to first solve/simplify the bracket followed by of (powers and roots etc.), then division , multiplication , addition and subtraction from left to right. .

Example :.

7 + (6 × 52 + 3) =   7 + (6 × 25 + 3).

7 + (150 + 3).

7 + (153).

7 + 153 .

Ans: 160. .

## Divisibility Rule

What is the divisibility by 2 Rule?.
Even numbers are multiples of 2. A number is even if ends in 0,2,4,6, or 8.
What is the divisibility by 3 rule?.
A number is divisible by 3 if the sum of its digits is divisible by 3.
372, for instance, is divisible by 3 since sum of its digits (3+7+2) is 12. And 12 is divisible by 3.
What is the divisibility by 4 rule?.
A number is divisible by 4 if the number\'s  last two digits are divisible by 4.
9,312, for instance, is divisible by 4 since its last 2 digits are 12. And 12 is divisible by 4.
What is the divisibility by 5 rule?.
A number is divisible by 5 if its last digit is a 0 or 5.
What is the divisibility by 6 rule?.
Since 6 is a multiple of 2 and 3, the rules for divisibility by 6 are a combination of the rule for 2 and the rule for   3.
Divisibility by 8 Rule.
A number passes the test for 8 if the las