Tuesday January 15, 2008
Number problems
I've just been looking at my son's maths homework, which is from the CGP Year Six Maths Workbook - Year Six in the UK is kids who are 10 to 11 years old. Here's the question:
I can think of four possible answers, depending on how you interpret the question:
- 6, i.e. the hundreds digit of 4695 is 6
- 600, i.e. the hundreds component of 4695 is 600
- 46, i.e. 100 goes into 4695 46 times, with 95 left over
- 46.95, i.e. 4695 ÷ 100
From previous experience with these books, it could be any of the first three possibilities, although the last one is an equally valid interpretation. No wonder the standard of maths in UK primary schools is so poor, if they have to use such frankly awful source material. Here's another example, from the next page:
17 × 6 + 98 ÷ 25 × 301 - 21 + 113 =
If you think the answer is 1376.92, i.e. (17 × 6) + (98 ÷ 25 × 301) - 21 + 113, you'd be wrong. The answer they seem to be expecting is 2500, i.e. ((((((17 × 6) + 98) ÷ 25) × 301) - 21) + 113). I know that's the case because the kids aren't allowed to use calculators, so the answer will be an integer value. So much for the rules of operator precedence...
p.s. Thanks to @kangcool for spotting the maths error in the original version ;-)
Posted by alanbur ( Jan 15 2008, 09:25:41 PM GMT ) Permalink Comments [3]
I agree about the first one, but I've read too many calculator manuals to agree about the second: the boxes are implying intermediate results should be taken.
(What answer does the book want for (a), anyway?)
- Stephen
Posted by Stephen on January 16, 2008 at 01:47 AM GMT #
My six year old is also working on placement and had a similar question ("How many tens in 127?"), with a note hand-written by the teacher at the side saying "I will accept two possible answers."
@Stephen: Looking at the other questions on the page, it seemed clear that the desired answer in our case was '2'.
Posted by David Edmondson on January 16, 2008 at 07:10 AM GMT #
@Stephen, I'm not sure, but I suspect the answer they are looking for is 6. What frustrates me with the books is that they often discard the mathematics notation the kids already know, and use very badly written English instead. What should be an exercise in mathematics turns into one of untangling linguistic uncertainty.
As for the second example, your calculator must be very old ;-) - most newer ones allow you to input the entire expression, and then perform the calculation when you press '=', so they get the operator precedence right.
Posted by Alan Burlison on January 16, 2008 at 09:50 AM GMT #