A quick maths question - would be really grateful!

[Creole]

Please help me with this, my Yr3 DS seem to think his method is right and won't listen to a word I say:

By how many mm is a strip measuring 25cm longer than a strip measuring 220mm?

470mm

30

(sorry - was never good at showing my working!)

30mm

25cm = 250mm

250 - 220 = 30

25 cm = 250cm

220mm + 250mm = 470mm

If he's unsure how to convert 25cm to 250mm by multiplying by 10, show him a ruler and the conversion will be plain to see!! Good luck in getting him to listen (or look!)

Hang on chaps, the strip in question is 250mm longer than 220mm.

250+220=470

30mm

DS is Yr3, I am going to ask him that one and see how he does it

multiply 25cm by 10 to get 250mm

then 250mm minus 220mm = 30mm

30mm
250mm-220mm=30mm

1cm=10mm

30mm see stealth's answer

30mm
25 = 250
220 is 220

250-220=30mm

You can read the question two ways.

the question is asking the difference between 2 strips of wood, not the strips added together.

The question basically asks: "how much longer is 250cm than 220 mm?" Doesn't it?

Asked dd who is supposed to be the maths whizz of her year 6 class and she said 30mm

Thank you guys, I knew the answer is 30mm, but he seems to think its 470mmm, which quite a few of you seem to think

It cannot be read two ways. The answer is 30mm. Key words are 'how many mm longer'

key word is BY.

clearly 30mm.

no 2 ways about it.

no, it's not by

30

Definitely 30mm as others have said. The question is "By how many mm is it longer"

The answer to the question "how many mm is a strip measuring 25cm longer than a strip measuring 220mm?" would be 470mm (ie how long is a strip that is 25cm longer than a 220mm long strip)

The answer to "BY how many mm is a strip measuring 25cm longer than a strip measuring 220mm?" is 30mm

it is longer by 30mm

Strip 1 is 220mm = 22cm
Strip 2 is 220mm + 25cm =?
220 + 250 = 470mm or 47cm

So Strip 2 is 47cm
Strip 1 is 25cm less = 22cm

no soup, the answer to that would be 30mm