Navigate Your Career Journey with Ease

Number Crunching Shortcuts: Your Numerical Reasoning Cheat Sheet

by | Sep 26, 2024 | Test Preparation Guides | 0 comments

You don't have to be a math whiz to handle numbers efficiently; mastering a few number crunching shortcuts can make a world of difference. Imagine effortlessly breaking down complex calculations into manageable steps, quickly estimating totals while shopping, or simplifying fractions on the fly. By incorporating techniques like mental addition tricks and quick subtraction methods, you'll find that numerical challenges aren't as daunting as they once seemed. Curious about how these strategies can transform your everyday tasks and boost your confidence with numbers? There's a whole array of practical tips waiting to be uncovered.

Mental Addition Tricks

Mental addition can be a breeze with a few handy tricks up your sleeve. First, break numbers into more manageable parts. For example, if you need to add 47 and 56, split them into 40 + 50 and 7 + 6. Add the tens (40 + 50 = 90) and the units (7 + 6 = 13). Then, combine those sums (90 + 13) to get 103.

Another useful trick is rounding. When adding 38 and 27, round 38 up to 40 and 27 down to 25. Add 40 and 25 to get 65. Since you added 2 to 38 and subtracted 2 from 27, the difference cancels out, giving you the correct total of 65.

You can also use the "near doubles" method. If you're adding numbers like 48 and 49, recognize that 49 is close to 48. Double 48 to get 96 and then add 1, resulting in 97.

Lastly, practice the "left-to-right addition" technique. For 356 + 467, first add the hundreds (300 + 400 = 700), then the tens (50 + 60 = 110), and finally the units (6 + 7 = 13). Sum these results (700 + 110 + 13) to get 823.

With these strategies, you'll master mental addition in no time.

Quick Subtraction Methods

Quick subtraction methods can save you time and reduce errors. One effective technique is breaking down numbers into more manageable parts. For instance, if you're subtracting 47 from 82, first subtract 40 (82 – 40 = 42), then subtract 7 (42 – 7 = 35). This way, you're dealing with simpler numbers, making it easier to avoid mistakes.

Another useful approach is rounding up and then correcting. Suppose you need to subtract 398 from 672. Round 398 up to 400, subtract to get 272 (672 – 400), and then add back the 2 you subtracted extra (272 + 2 = 274). This method leverages easier, rounded numbers and ensures accuracy.

You can also use complements to simplify subtraction. If you're subtracting 68 from 100, think of 100 – 68 as 100 – 70 + 2. Subtract 70 to get 30, then add back the 2 to get 32. This strategy works well when dealing with numbers close to a base like 100 or 1000.

Multiplication Shortcuts

Mastering subtraction techniques can significantly boost your numerical reasoning skills, but don't overlook the power of efficient multiplication shortcuts. When you're pressed for time or dealing with large numbers, these techniques can save you valuable seconds.

First, let's talk about multiplying by 9. Instead of traditional multiplication, think of it as multiplying by 10 and then subtracting the original number. For instance, 9 x 7 becomes (10 x 7) – 7, which equals 70 – 7, or 63.

Next, consider doubling and halving. If you need to multiply 14 by 5, double 14 to get 28, then halve 5 to get 2.5. Now multiply 28 by 2.5, which is easier and gives you 70.

For squaring numbers ending in 5, use this shortcut: take the first digit, multiply it by itself plus one, then append 25. For example, 25 squared is (2 x 3) followed by 25, or 625.

When multiplying two numbers close to 100, use the formula: (base + excess) x (base + other excess). For example, 103 x 107 becomes 100 + 3 and 100 + 7. Multiply the base (100) by itself, then add the product of the excesses (3 x 7).

These shortcuts can make multiplication quicker and more intuitive, helping you solve problems efficiently.

Easy Division Techniques

Dividing large numbers doesn't have to be a cumbersome task. You can break down division into simpler steps. Start by estimating. If you need to divide 987 by 3, round 987 to 990. Dividing 990 by 3 is easier and gives you 330. This estimate gets you close to the actual answer.

Use the distributive property. For example, to divide 156 by 4, split 156 into 120 and 36. Divide each part by 4 (120 ÷ 4 = 30; 36 ÷ 4 = 9), then add the results (30 + 9 = 39).

Another trick is to simplify both the dividend and divisor. If you're dividing 144 by 12, you can simplify to 12 ÷ 1, since both numbers are divisible by 12. The answer is 12.

For long division, break it into smaller chunks. Divide the first few digits that make a number larger than the divisor. Bring down the next digit only when needed. For example, in 154 ÷ 7, start with 15 ÷ 7 to get 2, then handle the remainder (15 – 14 = 1) by bringing down the next digit (4) to get 14, which divides evenly by 7 to give 2. The answer is 22.

These techniques make division faster and easier!

Fast Percent Calculations

Calculating percentages quickly can save you time and effort, whether you're shopping, budgeting, or working on a math problem.

One of the simplest tricks is to break the percentage into manageable parts. For example, if you need to find 15% of 60, first find 10% by moving the decimal one place to the left, giving you 6. Then, find 5% by halving that 10%, giving you 3. Add these results together: 6 + 3 = 9. So, 15% of 60 is 9.

Another handy shortcut is the "Rule of Nines" for estimating. If you need to find 9% of a number, you can multiply by 10% and then subtract the original number from the result.

For instance, to find 9% of 50, calculate 10% of 50 (which is 5) and then subtract 0.5 (10% of 50), giving you 4.5.

Simplifying Fractions

When you simplify fractions, start by finding common factors between the numerator and the denominator.

Once identified, divide both by their greatest common factor to reduce the fraction to its lowest terms.

This process makes calculations easier and results more understandable.

Finding Common Factors

One of the foundational skills in numerical reasoning is finding common factors to simplify fractions. When you've got a fraction, say 18/24, identifying common factors between the numerator and denominator helps.

First, list the factors of both numbers. For 18, the factors are 1, 2, 3, 6, 9, and 18. For 24, they're 1, 2, 3, 4, 6, 8, 12, and 24. Notice the common factors: 1, 2, 3, and 6.

The greatest common factor (GCF) here is 6. To simplify the fraction, divide both the numerator and the denominator by the GCF. So, 18 divided by 6 is 3, and 24 divided by 6 is 4. Therefore, 18/24 simplifies to 3/4.

You can use this technique with any pair of numbers. Another example: for 45/60, list the factors of 45 (1, 3, 5, 9, 15, 45) and 60 (1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60).

The common factors are 1, 3, 5, and 15, with 15 being the GCF. Divide both terms by 15, resulting in 3/4. Practicing this method improves your numerical reasoning skills significantly.

Reducing to Lowest Terms

To reduce a fraction to its lowest terms, you need to simplify both the numerator and the denominator by their greatest common factor (GCF). First, find the GCF of the numerator and the denominator. The GCF is the largest number that divides both numbers without leaving a remainder.

Once you've identified the GCF, divide both the numerator and the denominator by this number. For example, if you have the fraction 24/36, the GCF of 24 and 36 is 12. Divide both 24 and 36 by 12, and you get 2/3. So, 24/36 simplified to its lowest terms is 2/3.

Make sure you always check if the fraction can be reduced further. If the GCF is 1, the fraction is already in its simplest form. For instance, 5/7 can't be simplified further because the only common factor is 1.

Practice makes perfect. Take fractions you encounter and reduce them to their lowest terms to become more comfortable with the process.

Estimation Strategies

When you need a quick answer, rounding numbers can save you time and effort.

Simplifying complex numbers makes mental math easier and helps avoid mistakes.

Additionally, using benchmarks like 50% or 100 can guide you to more accurate estimates.

Rounding for Quick Calculations

Rounding numbers is a powerful tool for making quick calculations and estimates, especially when you're pressed for time. It's all about simplifying complex numbers into more manageable figures without losing too much accuracy. For instance, if you're adding 493 and 278, rounding them to 500 and 300 respectively makes the math quicker. You get an approximate sum of 800, which is close enough for many practical purposes.

To round numbers effectively, follow these basic steps: identify the place value you want to round to, look at the digit immediately to the right, and decide whether to round up or down. If the digit is 5 or higher, round up. If it's 4 or lower, round down. This method works for all basic arithmetic operations like addition, subtraction, multiplication, and division.

Rounding can also be useful in real-life scenarios like budgeting or time management. When you need to estimate the cost of groceries or the time it will take to complete a task, rounding numbers can provide a quick and reasonably accurate answer.

Simplifying Complex Numbers

Estimating complex numbers can greatly streamline your calculations and boost efficiency. When you encounter large or unwieldy numbers, break them down into more manageable parts. For instance, if you're dealing with 5978, think of it as 6000 for quick estimates. This method isn't about precision but about getting a close enough answer fast.

Use rounding strategically. If you need to multiply 47 by 82, round them to 50 and 80 respectively. Your rough estimate, 4000, gives you a ballpark figure. This can be particularly useful in multi-step calculations, where exact numbers can bog you down.

Don't be afraid to drop insignificant digits. When adding 3987 and 4503, consider them as 4000 and 4500. The sum, 8500, is close enough for most practical purposes. Remember, your goal is efficiency, not pinpoint accuracy.

Leverage patterns and common number properties. For example, recognize that multiplying by 5 is easy if you first multiply by 10 and then halve the result. So, 36 times 5 becomes 360 divided by 2, giving you 180 quickly.

These estimation strategies help simplify complex numbers, making your numerical reasoning quicker and more intuitive.

Using Benchmarks Effectively

Harnessing the power of benchmarks can revolutionize your estimation strategies. Benchmarks are familiar numbers or reference points that make calculations quicker and more intuitive. For example, if you're trying to estimate the total cost of several items priced around $4.75, round each to $5. This slight adjustment speeds up your calculations and provides a close approximation.

Use benchmarks like 10, 50, or 100 for larger numbers. If you're adding 47 and 53, round them to 50 each. Your mental math becomes simple: 50 + 50 = 100. This approach minimizes errors and keeps your calculations manageable.

Benchmarks are also invaluable in percentages. If you need to find 23% of 80, round 23% to 25% and 80 to 100. Now, calculate 25% of 100, which is 25. Adjusting your benchmark provides a quick, reasonable estimation.

When working with time, benchmarks simplify conversions. For instance, converting 125 minutes to hours is easier by rounding 125 to 120. You know 120 minutes equals 2 hours, making your estimation straightforward.

Incorporate these benchmarks into your daily calculations, and you'll find that your numerical reasoning sharpens. You'll save time, reduce errors, and handle numbers with newfound confidence.

Using Calculators Efficiently

Mastering calculator use can drastically improve your efficiency in numerical tasks. First, familiarize yourself with the calculator's functions. Spend a few minutes exploring the keys and features. It'll save you time when you need to perform complex calculations quickly.

Next, use the memory function. Store intermediate results to avoid re-entering numbers, which minimizes errors and speeds up your process. For instance, use the M+ button to add a number to memory and MR to recall it.

Don't forget about parentheses. Properly using them ensures the calculator follows the correct order of operations, just like in manual calculations. For example, input (3+2)×7 to get the right result, rather than getting tripped up by incorrect sequencing.

Also, practice using shortcuts for repetitive tasks. If you often calculate percentages, learn the specific steps your calculator requires to do this efficiently. Many calculators have dedicated percentage keys or functions.

Lastly, keep your calculator handy and in good condition. Replace batteries regularly or keep it charged. A reliable calculator is crucial for uninterrupted work.

Conclusion

By mastering these number crunching shortcuts, you'll boost your mental math skills and tackle everyday numerical challenges with ease. From quick additions to fast percent calculations, these techniques will make you more efficient and accurate in your daily tasks. Practice consistently, and you'll soon find yourself navigating through calculations effortlessly. Remember, with these tips, you're not just improving your math skills—you're gaining confidence in handling numbers anytime, anywhere.

Get Mometrix Preparation

Written By David Isaac

About the Author

Career consultant with over 15 years of experience in helping job seekers navigate the complexities of the hiring process. His insights and strategies have empowered countless individuals to achieve their career goals.

Related Posts

0 Comments

Submit a Comment

Your email address will not be published. Required fields are marked *