What is 4/5ths of 7/10ths? Maths homework nightmare! And how do you work it out?

[GossipMonger]

TIA

hmmm turn it into 50ths first?

and...........???

Multiply 4/5 by 7/10 = 28/50

Just as 1/2 of 1/5 is 1/2 x 1/5 = 1/10

4/5 of 7/10 means multiply the 2 fractions. You need to multiply the numerators together and then multiply the denominators together.

So ...

4 x 7 all over 5 x 10 ... Which gives you 28/50 ... You can then cancel to 14/25

Hope this helps

Convert to decimal?

So 4/5 = 8/10 = 0.8
7/10 = 0.7

0.8 x 0.7 = 0.56

Then convert back to a fraction.

runs to find DH to find out how

28/50, yes? 14/25? or have i totally forgotten it all?

Multiply them out - same as saying 0.8 times 0.7?
So multiply the numerators (top numbers) by each other, and the denominators (lower) by each other, then find the lowest common denominator.

Turn it into decimals.... .8 x .7 = .56

Which is 14/25

Or 4x7 / 5x20 = 28 / 50 = 14 / 25

In maths 'of' means the same as times.

This question therefore is the same as 4/5 x 7/10.

To multiply fractions multiply the tops together and the bottoms together. In this case 4x7 = 28 and 5 x 10 = 50. The answe us 28/50. You can cancel that to 14/25 by dividing top and bottom by 2.

7/10ths = 0.7

4/5 = 80%

So you want 0.7 x 80 / 100 = 0.56

turn the 7/10ths in 100th

70/100ths

work out 1/5th

14/100ths therefor 4/5ths is 56/100ths

then simplify the fraction

23/50

I phone + wine = 20 instead of 10

I think....

ok ignore me

If you are doing this for secondary school maths you definitely need to keep it as fractions and not change it to decimals when working it out btw. Thinking of it like decimals can help in this case a little, but when you get to thirds and other fractions it won't help!

Workshy your method is fine, and a nice way to think it through, you have just made a little mistake dividing 56 by 2. 56 / 2 = 28 which gives the right answer!

doh!

it's been a long day!

how come I can do the hard bit but not the easy bit lol

These maths problems are all the same.
They give you a problem in English language ...
that you have to translate into Maths language ...
then solve the Maths.

If I can't remember what the 'of' means then I always think of pizza. If I said "I have half a pizza, do you want half of it?" you would think "half of a half? That's a quarter of a pizza". This is exactly the same: for the 'half of a half' you did 1/2 times 1/2 which gives you 1/4 (cos the top is 1x1=1 and the bottom is 2x2=4).
So for this problem (4/5 of 7/10) the answer is 28 on the top (4x7) and 50 on the bottom (5x10) so 28/50ths or, to be more tidy, 14/25.

ooh you lot are great!

Thank you.

xx

My tiny brain just exploded