PLEASE CAN SOMEBODY HELP ME WITH THIS MATHS QUESTION THANKS

11 Plus Maths – Preparation and Information

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INONOTHING
Posts: 14
Joined: Sun Mar 08, 2009 4:36 pm

PLEASE CAN SOMEBODY HELP ME WITH THIS MATHS QUESTION THANKS

Post by INONOTHING »

hi all

i hope that somebody can explain this maths problem to me

0.1 x 0.1 = 0.01

how can this be?

i thought the rule was always that multiplying or adding something makes the number bigger - but the answer to 0.1 x 0.1 is 0.01 which is a smaller number

how can this be?

can anybody explain this to me as it is baffling me

many thanks X

inonothing
HR
Posts: 15
Joined: Mon Oct 08, 2007 10:01 am
Location: Herts

Post by HR »

I'll try....

If you multiply a number by a decimal, you make it smaller.

For example, 0.5 is 1/2 (a half) so if you multiply 2 by 0.5 you are working out what half of 2 is so

0.5 x 2 = 1

In your example, think of 0.1 as 1/10 or one tenth. You need to find out what one tenth of one tenth is so the answer must be smaller than one tenth.

Hope that helps!?
Complete Novice
Posts: 162
Joined: Sat Jan 12, 2008 7:14 pm

Post by Complete Novice »

If you convert 0.1 into a fraction ie 1/10 instead, it makes it easier to visualise what is happening. When you multiply something by 1/10 what you are actually doing is multiplying it by 1 and dividing it by 10 hence the reason it is getting smaller as a result of a multiplication.

1/10 x 1/10 = 1/100 which in decimals is 0.01.

I hope this helps but I'm sure someone will be along with a better explanation soon.

CN
dadofkent
Posts: 515
Joined: Tue Jan 01, 2008 2:05 pm

Post by dadofkent »

The above give the correct idea as to why the answer becomes smaller.

The actual arithmetical process is quite easy.

0.1 x 0.1

For the moment ignore the decimals and just multiply the numbers

1 x 1 = 1

Now look at the total number of decimal places in the original equation, that is the total number of digits in the two numbers to the right of the decimal point. The total is 2 decimal places

0.1 (1 digit to the right) x 0.1 (1 digit to the right)

Therefore the final answer will have 2 decimal places, or two digits to the right of the decimal point.

1 x 1 = 1

0.1 x 0.1 = 0.01

0.2 x 0.2 = 0.04

0.2 x 0.02 = 0.004

2.1 x 0.02 = 0.042
fed up
Posts: 160
Joined: Mon Jan 12, 2009 5:55 pm

Post by fed up »

If you think of 0.1 at one tenth, then the sum is

one tenth * one tenth

or one tenth of one tenth

which is one hundredth (or 0.01)
yoyo123
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Joined: Mon Jun 18, 2007 3:32 pm
Location: East Kent

Re: PLEASE CAN SOMEBODY HELP ME WITH THIS MATHS QUESTION THA

Post by yoyo123 »

INONOTHING wrote: i thought the rule was always that multiplying or adding something makes the number bigger - but the answer to 0.1 x 0.1 is 0.01 which is a smaller number

how can this be?

can anybody explain this to me as it is baffling me

many thanks X

inonothing
imagine a bar of chocolate with 10 squares.

0.1 =1/10 so 1/10 of the bar is 1 measly square!

now cut this square into 10 pieces again, (so you hava tenth of a tenth of a bar)
you get even less chocolate.
SunlampVexesEel
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Joined: Fri Jul 06, 2007 9:31 pm

Re: PLEASE CAN SOMEBODY HELP ME WITH THIS MATHS QUESTION THA

Post by SunlampVexesEel »

INONOTHING wrote:i thought the rule was always that multiplying or adding something makes the number bigger
Nope. That's not a rule in maths.
Adding a positive thing to a something makes it bigger, adding a negative thing to a thing makes it smaller.
Multiplying a thing by something bigger than 1 makes it bigger (numerically), mutlipying a thing by something smaller than 1 makes it smaller.
Multiplying a thing by something negative makes it negative, unless it's already negative, in which case it becomes positive.
:lol:
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