Finding a factor
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Finding a factor
Can people help please? I don't know what to start. The question is - The factors of a number add up to 13. What is the number? How do we do this please?
Thank you
Thank you
Re: Finding a factor
Factors are 2 numbers which you multiply together to make a given number..
E.g factors of 12
are 1, 2, 3, 4, 6 and 12. ( 1x 12; 2x6; 3x4)
so for this you could find 2 numbers which add up to 13 and multiply them together.
There is more than one answer, was it a multiple choice question?
E.g factors of 12
are 1, 2, 3, 4, 6 and 12. ( 1x 12; 2x6; 3x4)
so for this you could find 2 numbers which add up to 13 and multiply them together.
There is more than one answer, was it a multiple choice question?
Re: Finding a factor
I think they want all the factors of a particular number, so start with 2:
the factors of 2 are 2 and 1 (2 is divisible by 2 and 1 only), so adding them together will get 3 (2+1=3)
then 3 - the factors are 3 and 1 only, so 3+1=4
for 4 - the factors are 4, 1 and also 2, because 4 is divisible by 2 also, so the sum of the factors will be 4+1+2=7
for 5 - the factors are 5 and 1 only, so 5+1=6
for 6 - the factors are 6, 1 and also 2 and 3, so 6+1+2+3=12
for 7 - the factors are 7 and 1 only, so 7+1=8
for 8 - the factors are 8, 1 and also 2 and 4, so 8+1+2+4=15
for 9 - the factors are 9, 1 and also 3, so 9+1+3=13 - BINGO!
hope that helps
the factors of 2 are 2 and 1 (2 is divisible by 2 and 1 only), so adding them together will get 3 (2+1=3)
then 3 - the factors are 3 and 1 only, so 3+1=4
for 4 - the factors are 4, 1 and also 2, because 4 is divisible by 2 also, so the sum of the factors will be 4+1+2=7
for 5 - the factors are 5 and 1 only, so 5+1=6
for 6 - the factors are 6, 1 and also 2 and 3, so 6+1+2+3=12
for 7 - the factors are 7 and 1 only, so 7+1=8
for 8 - the factors are 8, 1 and also 2 and 4, so 8+1+2+4=15
for 9 - the factors are 9, 1 and also 3, so 9+1+3=13 - BINGO!
hope that helps
Re: Finding a factor
Doh! How many times do I tell my pupils......
"Read The Question!"
"Read The Question!"
Re: Finding a factor
The number must be less than 13 so I would have worked down from there ...
13 - can't be
12 - has lots of factors so not that
11 - no - it's prime so 11 + 1 = 12
10 - again too many factors
9 - yes, 1 + 3 + 9 = 13 (what do you notice about the sum of factors of a square number?)
13 - can't be
12 - has lots of factors so not that
11 - no - it's prime so 11 + 1 = 12
10 - again too many factors
9 - yes, 1 + 3 + 9 = 13 (what do you notice about the sum of factors of a square number?)
Re: Finding a factor
Sorry everyone for late reply - Internet went for long spaces of time. DH thought it only worked when we asleep
I think we need to play with factors to get this. Your replies so helpful. Thank you
I think we need to play with factors to get this. Your replies so helpful. Thank you
Re: Finding a factor
Lots and lots of board and dice games and interactive stuff online if you goggle factor games. I play them with my pupils, the competitive spirit takes over and they can spot them really quickly!
Eta: I meant google!
Eta: I meant google!
Re: Finding a factor
Thank you yoyo123. I look for them.
Re: Finding a factor
Please see Khan Academy videos on youtube. My DS was always confused till he saw those and now he is very confident/quick and accurate. You can see them for other topics as well.
Re: Finding a factor
Please don't use Khan Academy without being aware of the issues with it from a maths teacher's point of view.
I won't go on about it, as I've mentioned this before, but its American and uses non-UK methods and vocabulary. It's more likely to confuse than help.
I won't go on about it, as I've mentioned this before, but its American and uses non-UK methods and vocabulary. It's more likely to confuse than help.