Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

I am still not sure what to do ok?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

Right the original ratio was 3 parts yellow to 7 parts blue. Or 3 : 7

So yellow first: 3 x 7 = 21

Now blue: 7 x 7 = 49

Quick check: 21 + 49 = 70

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

I think maybe we should look back at dividing by 10:

Can you do these divisions by 10:

(1) 80 divided by 10

(2) 66 divided by 10

(3) 0.45 divided by 10 (this is more difficult)

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

Ok steveb mandy here could you. Give me some to do for morrow night as I am having trouble with do them ok?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

Can you give me an idea of how many questions to set?

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

Could you send me 3 to do ok?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

Okay I will email you shortly.

(EDIT: By the way for the benefit of anyone else reading this I sent 3 questions on division by 10 which Mandy replied to with all 3 correct. I then sent some questions on multiplication by 10 and 100 and then one divide by 100 question at the end.)

*Last edited by SteveB (2013-04-01 07:32:31)*

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

hi steveb mandy here the answer to the question you sent me are

Q1 67 X 10 = 6.7

Q2 0.91 X 10 = 0.091

Q3 4.7 X 10 = 0.47

Q4 0.34 X 100 = 00.034

Q5 89 X 100 = 0.89

Q6 65 DIVIDED 100 = 65.0

AM I RIGHT ?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

Q1 67 X 10 = 6.7

You have divided by 10 rather than multiplied by 10.

Q2 0.91 X 10 = 0.091

Same again here....

Q3 4.7 X 10 = 0.47

and here

Q4 0.34 X 100 = 00.034

Here you have divided by 10, but you were supposed to times by 100.

Q5 89 X 100 = 0.89

Here you have divided by 100.

Q6 65 DIVIDED 100 = 65.0

Here you have simply added point zero on the end. Doing this does not actually change the value of the number, but is sometimes

useful to help with a calculation. In other words 65 = 65.0

I think the problem here is understanding the question. Do you want to have another attempt at those?

SECOND EDIT:

I have sent 2 emails to you (Mandy) about this and I hope they have been of some help. Just in case they have not got

through here are a few notes on multiplication by 10 and 100, and division by 10 and 100.

Let us consider a number like 27.34

It can be thought of as 2 tens, 7 units, 3 tenths and 4 hundredths as shown below:

tens units tenths hundredths

2 7 . 3 4

To divide by ten the numbers go this way one space ------->

<--------- To multiply by ten the numbers go this way one space.

When we divide by 10: tens become units, units become tenths, tenths become hundredths, hundredths become thousanths ......(etc)

When we multiply by 10: hundredths become tenths, tenths become units, units become tens, tens become hundreds ........(etc)

So if we successively divide by 10:

27.34 becomes 2.734 then 0.2734 then 0.02734 then .....(etc)

If we successively multiply by 10:

27.34 becomes 273.4 then 2734 then 27340 then 273400 .....(etc)

Do not spend too long on these questions. If they are taking more than about 20 seconds each to do then something is wrong.

*Last edited by SteveB (2013-04-01 07:26:15)*

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

Hi steveb mandy here. I will do them again for you tomorrow ok as it will take me some time ok? I have sent you an email ok?

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

Hi steveb mandy here. The answer to the. Question are

Q1 = 67 x 10 = 670.0

Q2 = 0.91 x 10 = 091.0

Q3 = 4.7 x 10 = 0.47

Q4 = 0.34 100 = 0.34.0

Q5 = 89 x 100 = 890.0

Q6 = 65 ÷ 100 = 6.5

Am I right this time or not?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

mandy jane wrote:

Hi steveb mandy here. The answer to the. Question are

Q1 = 67 x 10 = 670.0

Correct. (670 would have been okay though, no need for the .0 bit at the end)

Q2 = 0.91 x 10 = 091.0

Not correct. The answer was 9.1 you have multiplied by 100.

Q3 = 4.7 x 10 = 0.47

Not correct. The answer was 47 you have divided by 10.

Q4 = 0.34 100 = 0.34.0

You have put in 2 decimal points here. Strictly speaking this is wrong, but if you meant 34.0 then that is okay.

Q5 = 89 x 100 = 890.0

Not correct. The correct answer was 8900

Q6 = 65 ÷ 100 = 6.5

Not correct. You have divided by 10. The correct answer was 0.65

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

Hi steveb mandy here. What do you want me to do next?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

I think I will ask you another one now:

5.6 divided by 10 ?

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

5.6 ÷ 10 = 59 am I right?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

No the answer to that one was 0.56

Okay try this: 5.6 multiplied by 10 ? (That is 5.6 x 10 ?)

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

Hi steveb mandy here 5.6 x 10 = 56 am I right?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

Correct.

Now how about this: 47 divided by 100 ?

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

47 ÷ 100 = 470 am I right?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

No that is wrong.

You have multiplied by 10. Try again (47 divided by 100).

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

Hi steveb mandy here. 47 ÷ 100 = 00.47 am I right?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

Yes that is correct. However it is more usual to write 0.47 rather than 00.47

Right how about: 34 x 100 ?

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

34 x 100 = 3400 am I right?

Offline

**SteveB****Member**- Registered: 2013-03-07
- Posts: 557

Correct.

Right how about this: 0.29 x 100 ?

Offline

**mandy jane****Member**- Registered: 2010-09-23
- Posts: 1,003

0.29 x 100 = 29 am I right?

Offline