Ascending order mix of decimals and fractions
Moderators: Section Moderators, Forum Moderators
-
- Posts: 1411
- Joined: Mon Mar 08, 2010 2:03 pm
Ascending order mix of decimals and fractions
Hello,
When DS has been ordering decimals or fractions, he's been taught to change them all to the same denominator (for fractions), or put them in tenths, hundredths columns etc (for decimals). However, neither he, nor I , can find a way to get some 'commonality' (ie the same denominator, or turning into decimals) for the following fraction/ decimal mix (WITHOUT using a calculator). Can anyone help? And, can anyone tell me if this mix would appear in an 11+ GS exam?
0.85, 4/5, 5/8
When DS has been ordering decimals or fractions, he's been taught to change them all to the same denominator (for fractions), or put them in tenths, hundredths columns etc (for decimals). However, neither he, nor I , can find a way to get some 'commonality' (ie the same denominator, or turning into decimals) for the following fraction/ decimal mix (WITHOUT using a calculator). Can anyone help? And, can anyone tell me if this mix would appear in an 11+ GS exam?
0.85, 4/5, 5/8
Seize the day ... before it seizes you.
Re: Ascending order mix of decimals and fractions
I guess I'd say that 4/5 is 8/10 so is 0.8, and that 1/8 is 0.125 (worth learning by heart) so 5/8 is 0.625 - then it is straightforward. I think also one might just have a "feel" for 5/8 being less than 8/10 --- it just "looks" closer to one half.
I would have thought that could be a GL assessment maths question.
I would have thought that could be a GL assessment maths question.
-
- Posts: 736
- Joined: Sat Dec 03, 2011 4:14 pm
Re: Ascending order mix of decimals and fractions
4 divided by 5 gives a decimal answer of 0.8 and 1 divided by 8 would give you 0.125.
You can use long division or 'bus stop' methods to change fractions to decimals
You can use long division or 'bus stop' methods to change fractions to decimals
-
- Posts: 1411
- Joined: Mon Mar 08, 2010 2:03 pm
Re: Ascending order mix of decimals and fractions
Ahem ... seems obvious now ... Thanks Mystery and Leanmeamum!
Seize the day ... before it seizes you.
Re: Ascending order mix of decimals and fractions
One way to get a feel of 5/8, is to think that 6/8 = 3/4 = 0.75.mystery wrote:I guess I'd say that 4/5 is 8/10 so is 0.8, and that 1/8 is 0.125 (worth learning by heart) so 5/8 is 0.625 - then it is straightforward. I think also one might just have a "feel" for 5/8 being less than 8/10 --- it just "looks" closer to one half.
I would have thought that could be a GL assessment maths question.
So 5/8 < 0.75, so must be the smallest.
Re: Ascending order mix of decimals and fractions
You only need to change them into the same denominator if you cannot judge their size or position on a number line in relation to each other.
-
- Posts: 1411
- Joined: Mon Mar 08, 2010 2:03 pm
Re: Ascending order mix of decimals and fractions
DS doesn't seem to be able to do this. Which particular fraction sizes should he know off by heart? 1/4, 1/2, 3/4, various eighths, sixteenths?Guest55 wrote:You only need to change them into the same denominator if you cannot judge their size or position on a number line in relation to each other.
Seize the day ... before it seizes you.
Re: Ascending order mix of decimals and fractions
Once you can order quarters then eight should be simple and sixteenths ...
Look at a fraction wall it can help some children 'see' the fractions in order.
Look at a fraction wall it can help some children 'see' the fractions in order.
-
- Posts: 484
- Joined: Thu Oct 18, 2012 10:41 am
Re: Ascending order mix of decimals and fractions
Think it's worthwhile memorizing the usual 1/2 , 1/4 , 3/4 as Guest55 says eights and sixteenths can be worked out, so other ones to memorise IMO are
1/3, 1/8 (meaning that you can work out sixths too if need be)
1/3, 1/8 (meaning that you can work out sixths too if need be)
-
- Posts: 66
- Joined: Mon Sep 10, 2012 9:44 pm
Re: Ascending order mix of decimals and fractions
Probably not the best way to do this example, but if you wanted to get the same denominator (i.e. 40), I would do the following:
0.85 = 85/100 = 17/20 = 34/40
4/5 = 32/40
5/8 = 25/40
0.85 = 85/100 = 17/20 = 34/40
4/5 = 32/40
5/8 = 25/40