Go forth and multiply

ryoishin

Ive spent most of my life assuming that multiplying meant to increase and dividing meant to make smaller.

So why when i multiply 400 x 0.864119 do I get 345.65?

And when I divide 400 by 0.864119 I get 462.90?

Has the universe changed all of a sudden.

alan4cult

ryoishin wrote: »

Ive spent most of my life assuming that multiplying meant to increase and dividing meant to make smaller.

So why when i multiply 400 x 0.864119 do I get 345.65?

And when I divide 400 by 0.864119 I get 462.90?

Has the universe changed all of a sudden.

Multiplying only increases the number when you multiply by a positive number greater than 1. If you multiply by a positive number less than 1 it makes it smaller

Dividing is the reverse. If you divide by a positive number greater than 1 you make it smaller. If you divide by a positive number less than 1 you make it bigger.

Don't divide by zero

rover84

ryoishin wrote: »

Ive spent most of my life assuming that multiplying meant to increase and dividing meant to make smaller.

So why when i multiply 400 x 0.864119 do I get 345.65?

And when I divide 400 by 0.864119 I get 462.90?

Has the universe changed all of a sudden.

yes the universe has changed

ryoishin

ryoishin wrote: »

Ive spent most of my life assuming that multiplying meant to increase and dividing meant to make smaller.

So why when i multiply 400 x 0.864119 do I get 345.65?

And when I divide 400 by 0.864119 I get 462.90?

Has the universe changed all of a sudden.

If you have, just say, 400 x 3, it's just another way of saying 400 + 400 + 400 = 1200 (that's the definition of multiplication, Basically).

If you have 400 x 0.5, you're just adding 0 + (half of 400) = 200.

Now, if you take the above to be true, what you've said for division must also be true (otherwise the above isn't true).

For example, if you have 400 x 0.5 = 200, and you divide both sides by 0.5, you'll get 400 = 200/(0.5).

Pherekydes

ryoishin wrote: »

So why when i multiply 400 x 0.864119 do I get 345.65?

Because 345.65 is 400 times bigger than 0.864119.

Michael Collins

How many half apples in three full apples? Answer: 6.

So 3 ÷ ½ = 6.

I think I also remember being taught "multiply = make bigger", "divide = make smaller". Another reason to suggest that maths is taught poorly in primary school.

chakotha

Maybe it should be called "application" rather than "multiplication"

3 applied to 100 is 300

0.1 applied to 100 is 10