Calculations

[@olusholajimoh870]

This is very helpful but would be nice to highlight or enlarge the calculation as workout is hidden in the background not hellpful

[@lsraheemali3900]

Hi Sureena.... I really like the way you explained dilutions in regards to Question D... However I was doing some questions until i came to a very similar question that instead of saying a 1 in 20 dilution like in question D it said a 2 in 10 and it threw me and I cant seem to get my head around it... Please help

[@akm5289]

Hi Sureena, quick question with the dilutions question, when you say if I have 0.2g in 1000ml, I’ll have 0.2g in 10ml and then the answer is 2g in 100ml which is 2% w/v. However, why would it be 2% and not 0.2% w/v? Because if you have 0.2g in 1000ml and 0.2g in 10ml, surely you would have 0.2g in 100ml...

[@SureenaSpeaks]

I fully understand what you mean, and I think explaining calculations through typing can be really difficult. But ultimately, if a question asks for an answer as % w/v, it wants you to give the answer as X in 100ml, so whatever you times or divide by on one side you have to do to the other side. The benefit of knowing more than one method is that if you don't like one particular method you don't have to use it, and instead use a method that you're more comfortable with (for example the method that is explained before the one above). With calculations, the more you practice the better your understanding will be, so best advice I can give you is to answer more questions similar to the one above and soon you'll find a technique and style that suits you :)

[@mohmad7982]

I would like to thank you. It was very helpful video.

[@SureenaSpeaks]

you're very welcome :)

[@zimg_igabyte]

Hi Sureena, I just wanted to ask, for the last question you said we can't disregard the 0.4 remaining from the 2.4 when calculating the number of tablets, if that value was 2.1 instead of 2.4, would we still round it up to 3 tablets in total?

[@SureenaSpeaks]

hiya! yep if it's asking for whole number of tablets :) In the same instance if a question asked how many people and the answer came to 2.1 - you can't have 0.1 of a person so you have to round up :) it's only really in these examples where you would round up like this :)

[@zimg_igabyte]

Sureena Speaks thank you ☺️☺️☺️☺️

[@reem4620]

Hello, do you have a bank of calculation questions that you can release?

[@user-tn6eg7yt4s]

Hate to be that person, but I think there might be a mistake on the part ratio photo in the (Image A). 1 to 4 and 1:4 should be five parts overall (1 part X and 4 parts Y, to use your example) while 1 in 4 would remain 4 parts overall (1 part X and the remainder Y, which is 3 parts). I'm trying to think about it logically, you're putting 1 part of X to 4 parts of Y and that makes five. If you have 4 parts, and 1 part is confirmed as X, then 3 parts of Y must be the remainder. I understand the confusion, when in regards to a formula (extemp preparation) the final ingredient will be given as (...to 400ml) and so the final volume would indeed be that, however in regards to this, it is being expressed differently. I don't know, I mean, my source literally is BBC KS3 bitesize where I've just googled it, so it's not exactly a dead cert. Either way, your videos have helped with revision. Cheers

[@SureenaSpeaks]

noo I'm glad you're being that person and bringing this to my attention thank you so much! You're completely right! Hahaa can't underestimate the power of BBC KS3 bitesize ;)

[@ioanna477]

thank you thats really useful :) what resources would you recommend for practising calcs?

[@onestepback2964]

Sureena for the last question, why do you not minus 4950 by 675 as you are using 3 tablets of 225mg?

[@SureenaSpeaks]

So 550mg represents the weight of the drug (your active ingredient) To make that 550mg you will get FROM (approximately) 3 tablets. if you times by 3 and got 675 then you're theoretically triple-ing the amount of active ingredient. With questions like this the working out will always be the same :) hope that helps :)

[@gamegigaginger7193]

hello and once again thank you for going simplifying these. love your videos, they awesome but if you could use a little more light in the room the overall quality of your videos will improve and they will become awesomer lol. thank you really appreciate it what youve done.

[@SureenaSpeaks]

aww you are completely right and I'm looking into that, thank you for the feedback I really appreciate it :)

[@bisijimoh2206]

Hi Sureena, just a little confused with image D. I thought we want the answer of weight of drug containing 10% moisture which will be 400mg and not the total weight of the drug (4000g). I am confused

[@SureenaSpeaks]

Hiya so the 3600g represents how much drug will be in 60L of solution. But we've been told that 10% = moisture so that means 90%is not with moisture, so this represents how much we actually have. But we want to know how much will be 100% hence the answer comes to 4000g. we are just told that 10% contains moisture so we need to take that into consideration when working out for 100%. hope that clears things up :)

[@bisijimoh2206]

I still don't get it🙉🙉, I'll have a look some other time. Thank you though, your videos are a blessing!

[@deesidumndeori7464]

This is the first time, i am actually sending you a message but am a big fan of yours and thank you very much for all the helpful videos, God bless you. My confusion regarding this question is that since we now know how much is in 60L which is 4000g, should we not find what needs to be added to that to give us 6%w/w as we did in the previous question since they are asking for that needs to be added? just a bit confuse because it said the concentration of the 60L is the 6%. thank you very much. God bless you

[@SureenaSpeaks]

Hiya! Aww thank you for your kind words! So there is 3600g in 60L not 4000g. And another way to phrase 6% is 6g in 100ml and what we're looking for is how much is in 60L - the concentration of 60L isn't the 6%. Hope that helps and good luck!!

[@haniyehfard2972]

😍