Directed Numbers
Zero is positive.
Zero is neither positive nor negative.
-a
Consider the polynomial
-x/3 +xy-2x^3y^2-9.
The coefficient of x
-1/3
0.12 = ___%
12
The cost price of a mug is $80. It is sold at a profit of 10%. What is the profit?
$8
Round off 20.76 g to the nearest 0.1 g.
20.8 g
The larger value of -3.1 and -3.9
-3.1
2(ab)
2ab
Consider the polynomial
-x/3 +xy-2x^3y^2-9.
The constant term minus the coefficient of
x^3y^2
-7
4% + 8% = ___%
12
The cost price of a mug is $80. It is sold at a profit of 10%. What is the selling price?
$88
Round up 7851 to the nearest 10.
7860
Give two directed numbers whose sum is zero.
e.g. (+3) + (-3)
(3a2b - ab) - (9ab - 2ba2)
5a2b - 10ab
The degree of the polynomial
-x/3 +xy-2x^3y^2-9.
5
30% of 1L = ___ mL
300
The selling price of a mug is $90. It is sold at a loss of 10%. What is the cost price?
$100
Round down 6481 to the nearest 100.
6400
-32 - (-3)2
-18
(-2a3b2c)3
-8a9b6c3
(2a - b)(3a + b)
6a^2 - ab - b^2
10% of x is 25. Find x.
250
The selling price of a mug is $72. It is sold at a loss of 10%. What is the loss?
$8
Estimate the total weight of the following:
51.2 kg, 49.7 kg, 48 kg, 50.4 kg, 52.8 kg
The total weight is about 50 kg x 5 or 250 kg.
{(-4)^2 [(-3)-(-2)]^3}/[(-2)^3]
2 or +2
[(10a^2b^5)(-9a^3b)]/(-15a^6b^3)
(6b^3)/a
(-5xy^3 + 2xy^3)^2
9x^2y^6
Joe has $800. He spends 20% of the money. How much is left?
$640
The jacket is sold at a discount of 20%. The selling price is $160. What is the marked price?
$200
Adrian bought
3 packs of chocolate at $18.2 each,
5 cans of soft drink at $6.8 each,
2 bags of potato chips at $12.5 each.
Estimate the total amount of money he has to pay.
The total amount of money he has to pay is about $(18 x 3 + 7 x 5 + 13 x 2), that is $115.
Use 3 directed numbers and 2 operations to get the answer -4.
e.g.
(-3) + (+5) - (+6)
e.g.
a^3b^2c -a+7bc
(1-2x)^2
1-4x+4x^2
The temperature decreases from 20 degrees Celsius to 15 degrees Celsius. What is the percentage change?
-25%
The jacket is sold at a discount of 20%. The selling price is $160. If the cost of the jacket is $120, what is the profit per cent?
66 2/3%
Peter bought
2 boxes of chocolate at $28 each,
5 cans of Coke at $8.3 each,
7 bags of crispy snacks at $18.3 each.
If he only has $250 cash, does he have enough money to buy all items?
The total amount
< $(30 x 2 + 9 x 5 + 20 x 7)
= $245
< $250
So he has enough money to buy all items.