GCSE Revision Quiz

23 × 17

• 391

• 390

• 392

• 381

Answer explanation

This is long multiplication. Remember, put the larger number on top and start multiplying with the ones!

Tags

long multiplication

Share £48 in the ratio 3: 5

• £12 : £36

• £18 : £30

• £9 : £39

• £18 : £35

Answer explanation

In order to solve this, you need to work out what the individual parts of the ratio are worth. Do this by adding them together:

3+5 = 8

Then, divide the total amount, by the total parts

48 $\div$ 8 = 6

So each individual part is worth £6.

Lastly, multiply each side of the ratio by 6, in order to find the missing values:


6 $\times$ 3 = 18

6 $\times$ 5 = 30

So the final answer is:

£18 : £30

Tags

ratio

Increase 120 by 10%

• 134

• 126

• 130

• 132

Answer explanation

This topic is percentage increase. The best way to do it is to create a decimal multiplier:

120 = 100%

You want to find 10% on top of that:

100% + 10% = 110%

Turn your 110% into a decimal:

$\frac{110}{100}=\ 1.1$

Multiply your original amount by the decimal to find the answer:

$1.1\ \times120\ =\ 132$
The alternative method is to find 10% by dividing your original number by 10, then adding it onto the original amount: $\frac{120}{10}\ =12\ \$ $120\ +12\ =132$

Its better if you can use the decimal method though, as it will allow you to deal with more complex questions involving percentages, especially compound interest.

Tags

percentages, percentage increase

Round 324 to 1sf

• 320

• 324.0

• 300

• 325

Answer explanation

You will be asked to round a number to a certain number of 'sf' or significant figures. This is an alternative to rounding to a certain number of dp.

To do this, you must count from the first number higher than 0 (so 0.0123 would be counted from the 1). Count along until you have the required number of significant figures, then use the rules of rounding to complete your answer. Complete the number with zeros.

In the question, the first significant figure is 3. The number is 324, so we need to maintain its size with zeros as place holders . Using the rules of rounding, we round down to 300.

Tags

significant figures, rounding

Estimate 19 × 47=

• 1000

• 893

• 890

• 950

Answer explanation

When you are estimating, you are rounding the numbers to the nearest, easy to calculate figures. In this case, that's 20 and 50.

20 $\times$ 50 = 1000
Watch out for the word 'estimate' in questions!

Expand 2(𝑥 + 3)

• 2𝑥 + 3

• 2𝑥 + 5

• 2𝑥 + 9

• 2𝑥 + 6

Answer explanation

This topic is expanding. When expanding brackets, you must multiply everything outside the bracket with everything inside it.

Tip: Remember $2x$ means $2\ \times\ x$ you don't need to write the $\times$ sign

Solve 3𝑥 + 2 = 11

• $x\ =\ 3$

• $x\ =\ 6$

• $x\ =\ 4$

• $x\ =\ 10$

Answer explanation

This topic is solving an equation. Remember to write out all the steps when answering questions like this:

$3x\ +\ 2\ =\ 11$

You need to get $x$ on its own. Begin by cancelling out the $+2$ by subtracting $2$ . This must be done on both sides of the equal sign.

$3x\ =\ 9$

Now, you need to get down to $x$ . You can remove the $\times3$ by doing the opposite, $\div3$ (again, on both sides)
$\frac{\text{3}x}{\text{3}}=\frac{9}{3}$ $x\ =3$

Tags

solving, algebra

What is the LCM of 15 and 20?

• 30

• 45

• 60

• 5

Answer explanation

The LCM or lowest common multiple is the smallest number that both numbers share in their times table.

In this instance, the easiest method is to write out the times tables for both numbers.

$1\ \times15\ =15$ $1\times20=20$
$2\times15\ =30$ $2\ \times20=40$
$3\ \times15=45$ $3\times20=60$
$4\times15=60$

The shared number in both times tables is $60$

2 + 3 × 4 =

• 14

• 20

• 24

• 12

Answer explanation

This topic is BIDMAS, the order of operations. You must do the multiplication first, then add the 2 onto the result.

 $\frac{2}{5}$  of 35

• 14

• 10

• 15

• 18

Answer explanation

Fractions! If you have a calculator, use the fraction button to do  $\frac{2}{5}\times35$  (Remember 'of' means multiply in maths)

If its non-calculator, divide your number by the denominator and multiply the resulting figure by the numerator (this applies to algebraic fractions as well).

 $35\ \div5=\ 7\ \ \$  

 $7\ \times2=14$