Techniques for Quick Calculations while Solving Previous Year Questions

Introduction
When solving previous year questions, it is important to be able to perform quick calculations in order to save time and increase efficiency. This can be achieved by employing specific techniques and strategies that help in simplifying calculations and finding answers more quickly. Here are some techniques that can be used:

1. Mental Math
Mental math refers to performing calculations in the mind without the use of pen and paper or a calculator. This technique can significantly speed up calculations, especially for basic arithmetic operations. Some mental math techniques include:

- Using shortcuts for addition and subtraction, such as rounding numbers and adjusting the calculations accordingly.
- Memorizing multiplication tables and using them to quickly multiply numbers.
- Breaking down complex calculations into simpler ones and solving them step by step.

2. Estimation
Estimation involves getting an approximate answer rather than an exact one. This technique is particularly useful when time is limited and the goal is to get close to the correct answer quickly. Estimation can be done by rounding numbers, using compatible numbers, or using the nearest whole number. It helps in quickly eliminating options in multiple-choice questions or in getting a rough idea of the answer before performing the actual calculation.

3. Cross Multiplication
Cross multiplication is a technique used to solve proportions quickly. It involves multiplying the numerator of one fraction with the denominator of the other fraction and vice versa. This technique is particularly useful in solving questions related to ratios, proportions, and percentages.

4. Unitary Method
The unitary method is a technique used to solve problems involving ratios and proportions. It involves finding the value of one unit and then using that value to find the value of the desired quantity. This technique is helpful in solving questions related to time, distance, speed, and work.

5. Use of Formulas
Memorizing important formulas and equations can greatly simplify calculations. By having these formulas at your fingertips, you can quickly substitute values into the formulas and find the answer without having to derive the formula each time.

Conclusion
When solving previous year questions, employing these techniques can help in performing quick calculations and finding the answers more efficiently. Mental math, estimation, cross multiplication, the unitary method, and the use of formulas are all valuable tools that can save time and increase accuracy. Practice using these techniques regularly to improve your speed and efficiency in solving mathematical problems.