In most cases, you will find it sufficient to work with just a couple of significant digits. Stores often price things just below an even dollar value, making this easy to do. Use $70.00 for $69.95, for example.
To calculate 10% of anything, move the decimal point one place to the left.
10% of 69.95 ≈ 10% of $70.00 = $7.00
It is often easy to compute double a number. This is good for
20% is double 10%
40% is double 20%
80% is double 40%
It requires a little more short-term memory, but it is not terribly hard to add a number to its double.
30% = 10% + 20%
60% = 20% + 40%
33% is very nearly 1/3, so division by 3 will get you there.
67% is very nearly double 1/3.
Then there are the calculations using 1/2, that is, division by 2.
5% = 10%/2
A 15% tip, for example, is 10% + half of 10%.
50% = (the entire amount)/2
25% = 50%/2
Well its easy
Fractions have numerator and denominator
Eg. 2/5 So 2 is numerator and 5 is denominator
Then % is always 100
So take the fraction and multiply by 100%
Example: In an examination you scored 25 out of 30. Calculate your percentage
Solution: You do this
25/30 * 100% (100 is over 1)
When given decimal change it into fraction(Convert it into fraction) then multiply by 100
|Hope it helps!
If the given value is - 38/45
multiply the numerator & denominator with 100
you'll get - 3800/4500
the divide with 45 the denominator and numerator
you ll get the answer 84.4/100 ie 84.4%
15% is 0.15.. Multiply 1,230.00 by 0.15.. Then you can get the 15percent of 1,230.. Perent is always per hundreds. 20% is 0.20.. 30% is 0.30.. Get it?
Its easy. Just divide the numerator (top) by the denominator (bottom) and multiply your ANSWER by 100. You will have a decimal and wherever the number(s) after the decimal is closest WHOLE number is to, that is your percentage.
To figure this without a calculator, you need to divide 22786 by 96879 and convert the quotient to a percentage. Depending on the accuracy you need, these numbers tend to lend themselves to making an estimate.
96879 is 3,121 short of 100,000, about 3%. So your answer will be about 3% larger than 22786/100,000 ≈ .228 = .228*100% = 22.8%.
3% of about 23 is about .69. Thus, a reasonable estimate of your answer is 22.8% + .7% = 23.5% (no calculator was involved)
My profession is engineering. Often, in my profession, answers within 10% are "close enough," and approximations tend to be used for quite a number of calculations. It is approximately true that, for numbers "near" 1, the inverse of a number (n) is given by (2-n). That is, the inverse of .97 is approximately 1.03, for example. This approximation is within 1% (or so) for numbers within 10% (or so) of 1. The approximation gets worse as you get farther away from 1. (1/1.2) is actually .833, for example, not .80--an error of about 4% of the actual value.
Your problem requires division by about 969, approximately equivalent to multiplication by 1031. Thus, the answer to your percentage problem is approximately 22.8*1.031, about 23.5 as shown above. Problems requiring only 3 significant digits of accuracy are usually done quite easily with pencil and paper (or, often, in your head). No calculator needed.
The easy way is to reduce everything. 100% is the maximum, that is our base. For eg to find 2% of £250,000.00 First I reduce the sum to £100,000 which becomes 100, 2% of 100 = 2 That gives me the answer. As we are using thousands 2 becomes 2000 so the answer is 2% of £250,000.00 = £5000.00
Broken down it is 2% 100 = 2 x 2 + 1 = 5 then add on the zeros as we are using thousands, ans 5,000
Anonymous I'm not very mathmatically gifted, but how I do it is. Work out 10%.. You just move the decimal point 1 space to the left. Then times that by 3. 10% = $7.99 $7.99 x 3 = $23.97 (round it up to 8. 8 x 3 is much easier to multiply, then just take away the 3 pence you added.) You then take the $23.97 away form $79.99 If you have to round it up to $24.00 away from $80.00 which is $56.00. 4 pence was added, so that must be deducted, so final answer would be $55.96
Round the price up to the nearest even dollar amount. Example 38,99 -$40. If there is a 20% discount you pay 80% so simply multiply 8X4=32 which is close to the actual amount which would be 31.19
I do a long and stupid way that's kind of like proportions, because I learned how to do it on my own self taught weird ways..
There are better ways out there but in case you don't find them, I do it like this:
X /100 = y / h
you want to fill in the blank of x and use the y and h as the number's you're comparing it to. Hopefully this makes sense. Then you solve it in some loop pattern. This is going to sound pretty wild, but here's an example:
X / 100 = 2 / 6
and you want to figure out what 2/6th percentage is, you will start with the 100, multiply it by 2, and then divide it by 6...(which is why I call it the loop thing, because I actually draw the path out on the paper so I don't get confused) when you finally reach X, it's 33.3
What percentage you want to find out, just multiply that with the actual amount and then divide the answer by 100. You will get the percentage of that amount. Or other easy steps, suppose you want to find out 20 % of 500, then remove last zero from 500, what you remain is 50 which is 10 % of 500.(by removing last zero you will remain 10 % of the amount),, now 10 * 2 = 20 so multiply 50 with 2 to get 20 % of 500. Isn't it easy.
Just type in the number you want, and if it's a percent, then after pushing in the number, press the % button.Then add, or do what ever with it.