Explanation

SPEED MATHS: Speed Maths is a method of solving mathematical problems quickly and accurately using mental calculation techniques, shortcuts, and tricks. It involves the use of techniques such as simplification, approximation, estimation, and pattern recognition to solve numerical problems in a time-efficient manner. Speed Maths is commonly used in competitive exams and is an essential skill for students and professionals who deal with numbers regularly. The objective of Speed Maths is to solve mathematical problems in the shortest possible time while maintaining accuracy.

IMPORTANT FORMULAS: There are several important formulas used in Speed Maths to quickly solve mathematical problems. Some of the most commonly used formulas are:

1. Squaring numbers ending in 5: (a5)^2 = (a x (a+1))25 For example, 35^2 = 3 x 4 = 12 and 25, so the answer is 1225.
2. Multiplying numbers close to 100: (100 – a) x (100 – b) = 10000 – (a+b) x 100 + ab For example, 98 x 96 = (100-2) x (100-4) = 10000 – 6 x 100 + 8 x 4 = 9408.
3. Divisibility by 2, 3, 4, 5, 6, 8, 9, 10, 11: A number is divisible by 2 if its last digit is even. A number is divisible by 3 if the sum of its digits is divisible by 3. A number is divisible by 4 if the last two digits are divisible by 4. A number is divisible by 5 if its last digit is 0 or 5. A number is divisible by 6

QUANTITATIVE APTITUDE

 

5

if it is divisible by both 2 and 3. A number is divisible by 8 if the last three

digits are divisible by 8. A number is divisible by 9 if the sum of its digits

is divisible by 9. A number is divisible by 10 if its last digit is 0. A number

is divisible by 11 if the difference between the sum of the digits at even

places and the sum of the digits at odd places is divisible by 11.

4. Percentage: To find x% of a number y, multiply y by x/100. For example,

25% of 80 = 80 x 25/100 = 20.

5. Profit and loss: Profit% = (Profit/Cost Price) x 100, Loss% = (Loss/Cost

Price) x 100, Selling Price = Cost Price + Profit, Selling Price = Cost Price –

Loss For example, if the cost price of an item is $50, and it is sold for $60,

the profit percentage is (60-50)/50 x 100 = 20%.

These formulas are just a few examples of the many techniques used in Speed

Maths. By mastering these formulas and techniques, you can solve

mathematical problems quickly and accurately, which is essential for success in

competitive exams and other fields that involve numbers.