# KS3 Numbers practice

```CALCULATOR IS PERMITTED FOR PERCENTAGES
CALCULATOR IS NOT PERMITTED FOR ROUNDING AND SI FORM &amp; EXPONENTS
Rounding and SI form:
1.
a.
b.
c.
2.
a.
b.
c.
3.
Round the following to 3 significant figures:
0.002012
0.0212123
3.12412
Round the following to 3 decimal places:
2.3123215
5.24524534
6.1231251
Use the SI form for the following (example: 0.0123 = 1.23 x 10-2)
Percentages:
1. Convert the following percentages into numbers.
Example: 105% = 1.05
a.
b.
c.
d.
e.
f.
2.
66.5%
0.5%
37.5%
22%
34%
25%
There is a pair of trousers on sale, which is priced at \$56. If there was a 20% sale, then
what is the initial price of the pair of trousers?
3. There is an artefact, which had its price increased by 17% from the original amount.
The price currently is now \$213. What is the initial price of the artefact?
4. A T-shirt is currently priced at \$123. If a 12% sale takes place in a month, then what
would the price of the T-shirt be in a month?
NOTE:
Compound interest equation
Final amount = Initial amount x (Rate)period
Example question:
If a bank offers 10% compound interest every 4 months, and if \$100 is invested for 2 years,
what is the amount of money that is received after the investment? Write answer to 2
decimal places.
Rate = 100% + 10% = 110% = 1.10
Initial amount = \$100
1
2 years = 24 months
Period = 24/4 = 6
Final amount = 100 x (1.1)6 = 177.16
5. If a bank offers 15% compound interest every 10 years and I invest \$1020 for 4.5 years,
how much do I receive after 4.5 years? Write answer to 2 decimal places
6. If a piece of artefact loses 10% of its price every year, how much would the artefact
be after 5 years if its initial price was \$123? Correct to two decimal places
7. A colony of bacteria has 1,000,000 bacteria. If a spray kills 50% of the bacteria present
in 10 minutes, how many bacteria would there be after:
a. 10 minutes?
b. 25 minutes?
Exponents:
1.
a.
b.
c.
d.
e.
2.
a.
b.
c.
d.
e.
3.
a.
b.
c.
d.
4.
a.
b.
c.
d.
5.
a.
b.
Calculate:
50
51
62
26
13
Calculate:
5-1
40.5
160.25
5-2
271/3
Calculate:
272/3
163/4
(22)2
(22/3)3
Calculate:
24 / 2 3
2 x 24
32 x 34
213 / 211
BONUS questions to consider. Calculate:
(-4)1/2
(213 x 823) / 211
2
```