My 9yr old grandson's math question....

I believe the way they teach children maths these days is similar to the way I was taught. We used Hundreds, Tens and Units, now they call units 'Ones' So numbers that have two digits and five 'ones' are 15,25,35,45,55,65,75,85,95. So as already said, the answer is 'No' there are nine.
 
SocketRocket said:
I believe the way they teach children maths these days is similar to the way I was taught. We used Hundreds, Tens and Units, now they call units 'Ones' So numbers that have two digits and five 'ones' are 15,25,35,45,55,65,75,85,95. So as already said, the answer is 'No' there are nine.
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Well if that is the logic they are following then there are only 8 as 55 has 2 fives.
 
ColchesterFC said:
1 + 8 = 9
9 x 2 = 18

So the two numbers added together (sum of its digits) multiplied by two (twice the sum) = the original number.
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There's some 'even more interesting' things (actually, it's 'trivia') about '9's....

If you reverse the 'product' in the previous puzzle (18 becomes 81) you actually have the square of the sum of the digits!
And if you cube the square route of the sum of those digits you get a number whose digirs add up to 'cube' of that square route!
And the result of all the factors of 9 (from 1 thru 20) add up to 9! (The above statement being 1 of those instances!)
 
Leftie said:
Square ROOT Foxy. Square root. :rolleyes:

We know you like accuracy. :)
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Thanks! I looked at it several times thinking "something doesn't look right"!

As for the original post/question...I think the answer is "No - there's 18" 15, 25, 35 etc plus 50, 51, 52 ...59 (not counting 55 twice).
 
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Foxholer said:
Thanks! I looked at it several times thinking "something doesn't look right"!

As for the original post/question...I think the answer is "No - there's 18" 15, 25, 35 etc plus 50, 51, 52 ...59 (not counting 55 twice).
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How does 50, 51, 52 etc have five ones (units)?
 
SocketRocket said:
I did explain. It says 'ones' these are what kids are taught today to use as 'units' or single digit integers.
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If that's the case, then, indeed, the answer is 'No, there are 9'. First I've heard of 'ones' being used that way though - as, I expect is the case for the OP! I had over-complicated the question. I guess it's not 'dumbing down'; merely 'making the terms consistent'. 'Ones' for me these days refers to a Stableford score (too often one of mine!)
 
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SocketRocket said:
I believe the way they teach children maths these days is similar to the way I was taught. We used Hundreds, Tens and Units, now they call units 'Ones' So numbers that have two digits and five 'ones' are 15,25,35,45,55,65,75,85,95. So as already said, the answer is 'No' there are nine.
Click to expand...
This logic makes the most sense to me. The way the question was worded sounded unusual, so "five ones" must mean something like what you've said. I'd say you've got it there.
 
Orikoru said:
This logic makes the most sense to me. The way the question was worded sounded unusual, so "five ones" must mean something like what you've said. I'd say you've got it there.
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Most of us oldies are used to terms like Hundreds, Tens and Units in basic maths but young children are taught to use the term 'Ones' instead of 'units'. I can understand why as it is more logical.
 
Based on the latest few replies, I can only hope the question seems to be a load of rubbish to us because we have it out of context. If it is within a page or chapter of a textbook talking about ones, tens, one hundreds etc, then the terminology is already covered, and the question would make a lot more sense.
 
SocketRocket said:
Most of us oldies are used to terms like Hundreds, Tens and Units in basic maths but young children are taught to use the term 'Ones' instead of 'units'. I can understand why as it is more logical.
Click to expand...

I was taught arithmetic using coloured rods for 1 to 10 - the smallest 'rod' was a white cube that I recall we referred to as a 'one'. A 'two' was red twice the length of the 'one' (obviously) etc.

That said - I still don't really understand the question. 15-95 there are 9 two digit numbers with 5 'ones' - which might be testing the child on their understanding that five 'ones' is the same as one 'five'. How old was the grandson again?

may well be the context and there may have been a 'number scatter' in which there were only 8 two-digit numbers with five 'ones' - and there might have been another question that asked - 'which one is missing?'
 
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SwingsitlikeHogan said:
I was taught arithmetic using coloured rods for 1 to 10 - the smallest 'rod' was a white cube that I recall we referred to as a 'one'. A 'two' was red twice the length of the 'one' (obviously) etc.

That said - I still don't really understand the question. 15-95 there are 9 two digit numbers with 5 'ones' - which might be testing the child on their understanding that five 'ones' is the same as one 'five'. How old was the grandson again?

may well be the context and there may have been a 'number scatter' in which there were only 8 two-digit numbers with five 'ones' - and there might have been another question that asked - 'which one is missing?'
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Its straight forward. The question is whether the proposition is true or false. Its false.
 
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