how do i calculate percentage stuff in my head for ex. something that is on sale?

Question

or if a homework questions asks ___ increased by 5%

thanks

and does anyone know how to use an ABACUS?

Answer 1

i am im advanced calculus in my last year of high school and percentages still foil me from time to time...if you are at a sale and something is 10% off, for example, and the product is $14.00, then move the decimal to the left one place and multiply by 1. If its twenty percent, then to the left one place, times by 2, and so on. For anything other than 0, like five, then move the decimal once to the left and multiply by 1.5
$14.00 - 10% = 1.4 x 1.0 = a savings of 1.4 dollars

Answer 2

i remeber from math class, you could find percents by changing them into a fraction. for example, 50% is the same as one half, so if something was marked 50%off, that would be the same as half off. the most basic ones we had to remember were:
1/4 = 25% , 2/4 = 1/2=50%, 3/4=75%, 4/4=1=100%
1/5=20%, 2/5=40%, 3/5=60%, 4/5=80%
1/3=33 1/3%, 2/3=66 2/3%
1/10=10%, 2/10=20%, ect.

if the question is asking how to increase something by 5%, all you have to do is divide whatever ___ is by 20 and then add the answer to ___.

an abacus is basically a column of bars with 10 beads on each bar. the first bar would, probably stand for ones, this means that one bead would equal 1 and 10 beads would equal 10. the next bar would equal tens, so one bead = 10 and 10 beads = 100. the next bar is hundreds, 1 bead = 100, 10 beads = 1000.

an abacus is most commonly used to count large numbers. for example, say you volunteered to count the number of people who attended a protest. you would use the beads to keep track of the people. on the first bar (ones) you would slide one bead across the bar for every one of the first ten people. you could only count upto ten people for the first bar , then for every ten people you counted, slide over one bead on the second bar to stand for tens, and slide the beads on the first bar back and start counting ones again. after another ten people, slide over a second bead on the second bar to stand for twenty people. after you reach one hundred, you would slide over one bead on the third bar for 100. then after a thousand, one bead on the fourth bar for (1000).

Answer 3

some caluclations are easier than others percentages are best done on a calculator using decimal format. 5% is expressed as .05 wihile 10% is .10. an increase of 5% to the total as your question states can be easily stated as 1.05%.

multiply the total questions by 1.05 to get the new total.

Answer 4

To increase y by 5% you can divide y by 100 (%) and then multiply by 105 (%).

or to do the same thing a different way- multiply y by 1.05 .