Addition is one of the four basic operations of arithmetic, with the others being subtraction, multiplication and division.
The addition of two whole numbers is the total amount of those quantities combined.
SHORTCUTS IN ADDITION:
Addition of numbers close to multiples of...
Multiplication of whole numbers is equivalent to a repeated addition; that is, the multiplication of two numbers is equivalent to adding as many copies of one of them, the multiplicand, as the value of the other one, the multiplier.
Normally, the...
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nCr=n!/
Question:
In how many ways 2 shirts and 3 pants can be selected from 5 shirts and 7 pants?
Answer:
Selecting 2 shirts out of 5 = 5C2 = 5!/
= 10
Selecting 3 shirts out of 7 = 7C3 = 7!/
=...
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Repeated elements
n!/(a!*b!)
Question:
In how many ways the letters of the word “ENVIRONMENT” can be arranged?
Answer:
n = 11
Let, a = 2 (E is repeated twice)
Let, b = 3 (N is repeated thrice)
Number of arrangements = 11!/(2! x 3!)
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Circular...
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Events
Dependent=multiplication
Independent =addition
Question:
There 3 busses from city A to city B and there are 5 busses from city B to city C. In how many ways a person can travel from city A to C through B?
Answer:
Choosing...
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Using the odd days
Question:
Find the day of birth of MS Dhoni (7 July, 1981), if 31 Dec 1999 is Friday
Answer:
Days after 7/7/1981 in 1981 = 177
Odd days by normal years from 1982 to 1999 = 14
Odd days...
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Using tanƟ
Ɵ tan
0 0
30 1/sqrt3
45 1
60 sqrt3
90 infty
Question:
A man on a boat saw a tower of height 100m at an angle of 60o. What...
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Maximum number of items per group
Take HCF
Question:
There are 40, 45 and 50 balls in three different colors. They have to be arranged in boxes such that all the boxes will have equal number of balls and same...
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Divisibility test
Divisibleby Rule
2 Last digit of a number should be 0,2,4,6, or 8
3 Sum of the digit should be divisible by 3
4 Last two digits of a number should be divisible by 4
5 Last digit of a number...
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Simple interest
SI=frac{PNR}{100}
P = Principle amount invested or borrowed
R = Rate of interest per term
N = Number of terms
Term = duration for which interest is calculated
Question:
A man invested Rs. 10000 at 4% per annum simple interest. What is the...
