with your brain...
Or the old-fashioned way -by counting it out on your fingers.
You multiply the number together - using a calculator if needed.
Using a calculator will make it easier
4 (using a calculator) for example 3*5 [enter]
Two choices: -- Multiply (the number) x (the percent using the percent % key). -- Multiply (the number) x (the percent), then divide the answer by 100. Either way, the claculator displays that many percent of that number.
Multiply by 0.9144
To multiply two numbers without a calculator, you can use the traditional long multiplication method: write the numbers down, align them by their rightmost digits, and multiply each digit of the bottom number by each digit of the top number, carrying over as necessary. Alternatively, you can use methods like breaking the numbers into smaller parts (distributive property) or using visual aids like arrays or grids. Estimation techniques, such as rounding the numbers to the nearest ten, can also provide a quick approximate result.
If you want it completely accurate:multiply the number by itself (that is two times done)multiply that result by the number (three times done)multiply the last result by the numberrepeat step 4 until the number has been multiplied by itself 100 times (ie repeat step 3 an extra 96 times)If you want an approximation:Take the logarithm of the number (using tables/slide rule/calculator)Multiply the number found in step 1 by 100Find the anti-log of the result of step 2 (using tables/slide rule/calculator)Depending upon the number and your calculator you may get it accurately or just an approximation by using the power button of a calculator, eg 2100 could be [2][xy][1][0][0][=]
try to find what number times the same numbers equals the number that you have.
Multiply both numbers by five- to get the fraction 85/100... which is 85%
Multiply the whole number times the numerator. Divide the product by the denominator.
Multiply 10.13 by 0.035
12 is 15% of 80.