formula to round to 1 gram

[basix101]

Hello,

Firstly thank you to anyone who can help me with this.

I sell seeds, and I regulary have to round seeds to 1 gram when I do my paperwork.

My problem is I struggle to do it.

What finally brought me here is:

If 50 seeds weigh 65mg how many are there in 1 gram?

It's not so much the answer I need but the formula to be able to do it regularly.

Again, thank in advance for any help given, it is sincerely appreciated.

 

[Deleted member 4993]

Hello,

Firstly thank you to anyone who can help me with this.

I sell seeds, and I regulary have to round seeds to 1 gram when I do my paperwork.

My problem is I struggle to do it.

What finally brought me here is:

If 50 seeds weigh 65mg how many are there in 1 gram?

It's not so much the answer I need but the formula to be able to do it regularly.

Again, thank in advance for any help given, it is sincerely appreciated.

Let's do some simpler problem - you'll "invent" the formula and will never forget it!!

Two marbles, identical , weighs 10 gms together.

How much does each one weigh? (how did you get the answer?)

How many marbles are there if the weight is 15 gms?(how did you get the answer?)

How many marbles are there if the weight is 30 gms or 45 gms or 105 gms?(how did you get the answers?)

In your particular problem you have to remember that 1 gm = 1000 mg

If you can answer the above questions - tell us - then we will help you invent your formula!!

 

[basix101]

Thank you,

OK I've got it (I think) 770 seeds make 1 gram.

I found the answer by:

50=65mg
ADD 0 to the ends of both = 500 = 650mg
ADD another 0 to the ends of both = 5000 = 6.5 grams
Double 5000 to 10,000 = 13 grams
10,000/13 grams = 770 seeds per gram

What I was hoping for was a magic solution something like "algebra"? where x = the seeds y = the amount, and z = 1 gram, so it would go something like plugging in numbers to get to 1 gram.

Not good at maths so I may not be making any sense at all! lol

Thank you for replying, it is appreciated.

 

[JeffM]

Thank you,

OK I've got it (I think) 770 seeds make 1 gram.

I found the answer by:

50=65mg
ADD 0 to the ends of both = 500 = 650mg
ADD another 0 to the ends of both = 5000 = 6.5 grams
Double 5000 to 10,000 = 13 grams
10,000/13 grams = 770 seeds per gram

What I was hoping for was a magic solution something like "algebra"? where x = the seeds y = the amount, and z = 1 gram, so it would go something like plugging in numbers to get to 1 gram.

Not good at maths so I may not be making any sense at all! lol

Thank you for replying, it is appreciated.

OK you get the right approximate answer your way, but it is cumbersome.

What Subhotosh Khan wanted you to do was to answer his questions so you would see HOW the simpler algebraic formula is put together. If you do the work yourself, you will never forget the formula and will understand why it works.

2 marbles weigh 10 grams. So 1 marble weighs how many grams? How did you figure that out?

So 50 seeds weigh 65 milligrams. So 1 seed weighs how many milligrams?

In short, if x = the number of seeds and y the weight of x seeds in milligrams and z = the weight in milligrams of one seed, z = what?

How many milligrams are there in a gram? 1000 right?

So if there are z seeds in one millgram, how many seeds are there in a gram?

 

[HallsofIvy]

Thank you,

OK I've got it (I think) 770 seeds make 1 gram.

I found the answer by:

50=65mg
ADD 0 to the ends of both = 500 = 650mg
ADD another 0 to the ends of both = 5000 = 6.5 grams
Double 5000 to 10,000 = 13 grams
10,000/13 grams = 770 seeds per gram

What I was hoping for was a magic solution something like "algebra"? where x = the seeds y = the amount, and z = 1 gram, so it would go something like plugging in numbers to get to 1 gram.

Well, you could have but thinking, rather than just remembering formulas, is always better and often more fun!

You could have thought of this as a proportions: \(\displaystyle \frac{x seeds}{1 gram}= \frac{50 seeds}{65 mg}\).

And now think either "1 gram is 1000 mg" or "1 mg is .001 g".

Using "1 gram is 1000 mg" gives \(\displaystyle \frac{x seeds}{1000 mg}= \frac{50 seeds}{65 mg}\)
so that \(\displaystyle x= \frac{50}{65}(1000)\) seeds.

Using "1 mg is .001 g" gives \(\displaystyle \frac{x seeds}{1 g}= \frac{50}{.065 g}\)
so that \(\displaystyle x= \frac{50}{.065}(1)\) seeds.

Of course, those two answers are exactly the same. 50/65= 0.769 so (50/69)(1000)= 769 while 50/.065 is 769.

So your "770" is awfully close but not exactly what I get.

Not good at maths so I may not be making any sense at all! lol

Thank you for replying, it is appreciated.

In your answer, I hope you understand that "add a 0 to the end" is really "multiply by 10".