Grade 8 Mental Math help?

Question

Here are just are few questions. Please try answering them, if you can't answer all of them, answer the ones you know. That will be greatly appreciated.

1) Complete the series:

1,8,27,64, ?,? Figure out what comes after 64 and tell me how the pattern works.

2) Give your answer in Arabic numerals.

D C L X V - C C X L I V = ? (It's a subtraction question) Please tell me what I'm subtracting in real numbers like 1,2,3.

3)One hectare is about the size of :

a) a tennis court
b) a hockey field

4) Multiplication is a quick way of:

a) adding unequal numbers
b) doubling numbers
c) adding tens and units
d) adding equal numbers

Also

5) When a 4/5 full jar holds 12L, how much does it hold when it's 1/2 full? Tell me how you work this out.

6) 0.027 = 2/? +7/?. Tell me how you work this out.

These are fraction questions.

Answer 1

1) The next number is 125

1^3 = 1
2^3 = 8
3^3 = 27
4^3 = 64
5^3 = 125

2) DCLXV = 665
CCXLIV = 244

So 665 - 244 = 421

421 = CDXXI

3) a hockey field

4) adding equal numbers

Bye

Answer 2

For number 5, use the equation 4/5 = 12L; multiply both sides of the equation by 5/4 to give you one on the left side and to find out how much a full jar holds (a full jar would be 1 jar). So 12L times 5/4 equals 15L (go ahead and do this on paper). Then you divide 15 by 2 to find out how much a half a jar would hold.

For number 6, rewrite the decimal as a fraction (27/1000) and you can see that this would be the same as 20/1000 + 7/1000, but your problem is written 2/? + 7/? so rewrite it as 2/100 + 7/1000 because this is equivalent.

Don't let this stuff get you down, it just takes a lot of practice and no matter what people are saying - it is worth learning. It will help you get a better job than if you don't learn it. Trust me..

Answer 3

1) These are all cubes. The number 1 is just 1^3. The number 8 is 2^3. And the number 27 is 3^3. 64 is 4^3. So the next one should be 5^3 which is 125.

2) I don't do Arabic.

3) A hectare is about 10,000 meters^2. Which would be 100 X 100 meters. When is the last time you saw a hockey rink or a tennis court 100 meters wide? Retarded question the answers is neither.

Answer 4

1.
1^3, 2^3, 3^3, 4^3,
5^3 = 125,
6^3 = 216.

2.
You add the numbers which each letter represents, except when a letter of lower value precedes one of higher value. In that case you subtract the lower from the higher.

D = 500
C = 100
L = 50
X = 10
V = 5
DCLXV = sum of these = 665

CC = 200
XL = 50 - 10 = 40
IV = 5 - 1 = 4
CCXLIV = 244

Difference = 421.

3.
10000 m^2 is more like a hockey field.

4.
(d). 5 * 4 = 4 + 4 + 4 + 4 + 4.
(b) is multiplication as well, but as it is only one specific example rather than a general description, it is not as good an answer as (d).

Answer 5

1^3, 2^3, 3^3, ... so 5^3 = 125 and 6^3 = 216 are next two terms.

665 - 244 = 421

A hectare is about 2.471 acres. Thus it is closest to a hockey field.

d) adding equal numbers

Answer 6

im sorry to say that you go to a prety demented school. i go to a very good catholic high school, and it isn't necessary or like, legal to know that complicated math. to answer some of your questions though, 3 is neither! ( a hectare is 10000 metres squared!) and 4 is b

Answer 7

1x1x1=1
2x2x2=8
3x3x3=27
4x4x4=64
5x5x5=125