View Full Version : Math Question

Hey!

I am a teacher and right now I forgot how to do something in math, (because right now I have several courses). So what I forgot is something simple. How do you take away percent from a whole number?

Example: $25 has a 40% discount. What is the new price? How do you do this, (using a calculator, because I am checking the students papers)

Thanks! :)

25 = 100

?? = 40

25*40/100 = ?? = 10 :tmb:

EDIT: Actually you want to know what 60% is, so...

25*60/100 = 15

Melonie Tomb Raider

24-05-06, 22:10

Well the way I always do it is multiply 40% to $25. Just make the percentage a decimal. .4 x 25 = 10. So that would be $10 off.

I'm pretty sure anyway. Some one correct me if I'm wrong.

Catapharact

24-05-06, 22:10

(40/100) x 25

0.40 x 25 = 10

Melonie Tomb Raider

24-05-06, 22:11

0.40 x 25 = 10

Looks like I was right after all. :p

Catapharact

24-05-06, 22:12

Looks like I was right after all. :p

You certainly were ;).

What do you teach btw? Not maths I hope... :D

Thanks! So far I am marking the kids work and this is what he wrote:

25 goes into forty once and there is 15 leftover so the answer is 1.15.

I asked him soo many times if he under stood and he always said "Yes, sir!" Well he'll be missing a few recesses.

Hmm well at least there's some logic in his answer...

Just 15 would've been correct :p

Melonie Tomb Raider

24-05-06, 22:17

Hi Cat! :wve: :hug: How are you? Honestly, I really do plan on signing on msn soon, when I have time to talk a lot lol. I've been caught up with things lately, and I'm about to go to a church function right now, but I'll try to be on later! :D

Oh, and I'm glad we could help you Horus. :) Hopefully that kid will learn how to correctly do his math questions from now on. :p

yes, I hope so. His report card now has another D- on it.

He drives kids crazy, the other day, he snuck behind a girl and cut of her hair.

Catapharact

24-05-06, 22:20

Sorry for the offtopicness ppl Lol!

Mel:

Hey no prob at all sweets :). Me just got a little time left online right now. Just got 7 more days worth of time off before hitting UAE for the summer. Just wanna say a good hi and how are you before going off :).

yes, I hope so. His report card now has another D- on it.

He drives kids crazy, the other day, he snuck behind a girl and cut of her hair.

:eek: How old is he? That's not really ... Normal :/

I teach grade 4 so about 10 or 11.

Hmm ah I guess it can happen there... Keep an eye on him tho :p

meansizzler

25-05-06, 00:53

Percentages, use to hate them when I was a kid but now there easy, do them in my head all the time, you know how to do them with a calcualtor now like, 35% of 250 is simply 35/100 * 250 = 87.5, now lets do that in your head...

Always start like this, you need 35% right so that's 3 lots of 10% and 1 lot of 5%...

10% of 250 is 25, if you can't work that out in your head you shouldn't be teaching math...

5% of 250 well is, you know 10% is 25 so 5% is halve that which is 12.5

now 35% is (3*10% + 5%) which is (3*25 +12.5) so (75+12.5) which is 87.5, simple huh?...

Well you get use ot the concept and soon you will be able to do stuff like 37 percent of say 125 without a calculator...

Lara Croft!

25-05-06, 13:21

Math thread???I don't even know why I checked it out......Brrrrrr*shivers*

I agree with meansizzler. Percentages are easy and can be done in your head if you work on 10% as a base. Converting most fractions into percentages are easy too if looked at logically. Using calculators for every thing breeds reliance on them. What do you do then if the batteries are flat?

tha_mattster

25-05-06, 13:45

I agree with meansizzler. Percentages are easy and can be done in your head if you work on 10% as a base. Converting most fractions into percentages are easy too if looked at logically. Using calculators for every thing breeds reliance on them. What do you do then if the batteries are flat?

post the question on Tomb raider forums. duh!

:vlol: Very good. Shows inititive! :tmb:

vBulletin® v3.8.9, Copyright ©2000-2015, vBulletin Solutions, Inc.