Quantitative Aptitude Important Formulas

Volume & Surface Area - Important Formulas,Tricks and Examples

Cuboid:
Volume = lbh
Surface Area = 2(lb + bh + hl)
Diagonal =√(l2 +b2 +h2)

Cube:
Volume = a3
Surface Area = 6a2
Length of diagonal = a√3

Sphere:
Volume = (4/3)πr3
Surface Area = 4πr2

Hemisphere:
Volume = (2/3)πr3
Curved Surface Area = 2πr2
Total Surface Area = 2πr2+ πr2 = 3πr2

Cylinder:
Volume = πr2h
Curved Surface Area = 2πrh
Total Surface Area = 2πrh + 2πr2 = 2πr(h + r)

Cone:
Volume = (1/3)πr2h
Curved Surface Area = πrl
Total Surface Area = πrl + πr2 = πr(l + r).

Post comment
Cancel
Thanks for your comment.!
Write a comment(Click here) ...

Numbers - Important Formulas,Tricks and Examples

The common number system is decimal number system.
The Decimal number system used base (or radix) as 10 . This means that the system has ten symbols or numerals to represent any quantity. These symbols are called Digits and they are: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

Types of Numbers

Natural Numbers:The numbers that are used for counting called Natural Numbers.These are infinite and start from the number 1 .
Ex : 1, 2, 3, 4, 5, 6 ........

Whole numbers:The whole numbers are just all the natural numbers plus zero.
Ex : 0, 1, 2, 3, 4, 5 .............

Integers: Integers incorporate all positive and negative numbers with zero.
Ex : .... –3, –2, –1, 0, 1, 2, 3 .....

Even Numbers: An even number is one that can be divided evenly by two leaving no remainder, such as 2, 4, 6, and 8.

Odd Numbers: An odd number is one that does not divide evenly by two, such as 1, 3, 5, and 7.

Rational Numbers: All numbers of the form p/q where p and q are integers (q ≠ 0) called Rational numbers.
Ex : 4, 3/4, 0, ….

Irrational Numbers: Irrational numbers are the opposite of rational numbers. An irrational number cannot be written as a fraction as p/q where a and b are integers.
the decimal values for irrational numbers never end and do not have a repeating pattern in them.please note ‘pi’ has never ending decimal places, is irrational.
Ex : pi, 2^1/2 , 3^1/2, 5^1/2 , 7^1/2 ..........

Real numbers: Real numbers include counting numbers, whole numbers, integers, rational numbers and irrational numbers.
Ex : 8, 6, 2, (3)^1/2 , 3/5 etc.

Prime Number: A prime number is a number which can be divided only by 1 and itself. The prime number has only two factors, 1 and itself.
Ex : 2, 3, 7, 11, 13, 17, …. are prime numbers.

Composite Number: A Composite Number is a number which can be divided evenly. Any composite number has additional factors than 1 and itself.
Ex : 4, 6, 8, 9, 10 …..

Co-primes or Relatively prime numbers: A pair of numbers not having any common factors other than 1 or –1. (Or alternatively their greatest common factor is 1 or –1)
Ex : 15 and 28 are co-prime, because the factors of 15 (1,3,5,15) , and the factors of 28 (1,2,4,7,14,28) are not in common (except for 1) .

Twin Primes: A pair of prime numbers is said to be twin primes if they differ by 2.
Ex : (3,5) , (5,7) , (11,13) , …

Algebra

(a+b)2 = a2 + 2ab + b2
(a-b)2 = a2 - 2ab + b2

(a+b)2 - (a-b)2 = 4ab
(a+b)2 + (a-b)2 = 2 (a2 + b2)

a2-b2 = (a-b)(a+b)

(a+b)3 = a3+b3+3ab(a+b) = a3+b3+3a2b+3ab2
(a-b)3 = a3-b3-3ab(a-b) = a3-b3-3a2b+3ab2

a3+b3 =(a+b)3-3ab(a+b) = (a+b)(a2-ab+b2)
a3-b3 =(a-b)3+3ab(a-b) = (a-b)(a2+ab+b2)

Test of Divisibility

Divisibility By 2 : A number is divisible by 2, if its unit's digit is zero or even (2, 4, 6, 8..).

Divisibility By 3 : A number is divisible by 3, if the sum of its digits is divisible by 3.

Divisibility By 4 : A number is divisible by 4, if the number formed by the last two digits is divisible by 4.

Divisibility By 5 : A number is divisible by 5, if its unit's digit is either 0 or 5.

Divisibility By 6 : A number is divisible by 6, if it is divisible by both 2 and 3.

Divisibility By 8 : A number is divisible by 8, if the number formed by the last three digits of the given number is divisible by 8.

Divisibility By 9 : A number is divisible by 9, if the sum of its digits is divisible
by 9.

Divisibility By 10 : A number is divisible by 10, if it ends with 0.

Divisibility By 11 : A number is divisible by 11, if the difference of the sum of its digits at odd places and the sum of its digits at even places, is either 0 or a number divisible by 11.

Divisibility By 12: A number is divisible By 12 if the number is divisible By both 4 and 3.

Divisibility By 13: A number is divisible By 13 if its unit’s place digit is multiplied By 4 and added to the remaining digits and the number obtained is divisible By 13.

Divisibility By 14: A number is divisible By 14 if the number is divisible By both 2 and 7.

Divisibility By 15: A number is divisible By 15 if the number is divisible By both 3 and 5.

Divisibility By 16: A number is divisible By 16 if its last 4 digits is divisible By 16 or if the last four digits are zeros.

Divisibility By 17: A number is divisible By 17 if its unit’s place digit is multiplied By 5 and subtracted from the remaining digits and the number obtained is divisible By 17.

Divisibility By 18: A number is divisible By 18 if the number is divisible By both 2 and 9.

Divisibility By 19: A number is divisible By 19 if its unit’s place digit is multiplied By 2 and added to the remaining digits and the number obtained is divisible By 19.

Divisibility By 20: A number is divisible by 20 if it is divisible by 10 and the tens digit is even.

Latest Updates

Direction

Swapnil start from his home and walked 35 km towards east, after that he turned to his right and walked 20 km. He again turned to his right and walks 35 km. Finally, he turned to his left and walked 20 km and reached his office. How far is his office from his home?

Numbers

How many 2 digit numbers are divisible by 6?

HCF and LCM

Find the smallest square number which is exactly divisible by 3, 5, 15, 18, 20 and 24?

HCF and LCM of two numbers are 82 and 574 respectively. if one of the numbers is 287, find the second number?

Numbers

How many numbers between 1200 to 1500 are multiple of 13?

Find the total number of terms in the series : -3, 1, 5, 9,............., 101 ?

Find the sum of the first 20 terms of the series : 8, -3, 11, -6, 14, -12, 17, -24,....... ?

Series

Find the missing term in the given series - 101, 120, 145, 168, (?), 224

Find the missing term in the given series - 11A13, 17E19, (?), 31O37, 41U43

Find the missing term in the given series - 2,4,8,3,9,27,4,16,(?),5,25,125

Agriculture

Which gas is fixed by Rhizobium bacteria present in the root nodules of a pea plant ?

Chemistry

The formation of sulphurous acid involves ?

The acid present in soft drinks is ?

The cathode of a dry cell is made of ?

The number of atoms present in the molecule of an element is known as its?

Physics

If the angle of incidence formed by a ray of light on a plane mirror is 37°, then the angle of refraction is?

A dynamo converts ?

If the time taken for hearing the echo of a girl's voice after reflection from a cliff is 6 seconds, calculate the distance of the girl from cliff ?