How to multiply by 12, using Trachtenburg’s Method.
The exam paper referred to in this post can be found here. For each question which is compatible with Ratio Grids, I work through a similar example, then you can try the actual exam question. The answers to the exam paper can be found here. This is a calculator exam.
You will need to be able to complete a ratio grid to follow this page – so watch this 2 minute video!
Similar to Question 4 – write a fraction as a percentage
Similar to Question 13 – A machine filling containers with items – how many left over?
Similar to Question 14: Drawing a Pie Chart
Similar to Question 16. How many marks needed to pass an exam?
Similar to question 17: Making Orange Juice
Similar to question 17b: Simplify a ratio (Calculator method)
Similar to question 19: Sharing money without knowing the total
Similar to question 20: Shopping with a ratio
Similar to question 23: Different sized boxes
Similar to question 28: Exterior angles in a polygon
- For the video of instructions, click HERE
- Worksheet about factorising numbers click here
- To download the worksheet factorising quadratics both numbers positive click here
- For the answers, click here
- For more practice (includes negative coefficients) click here
- For harder questions (larger coefficient of x squared) click here
If you are not already confident using RATIO GRIDS then watch this video first!
What is 35% of £14?
What is 15% of £85?
My savings target is £5500. I have saved £2640. What percentage have I saved?
Jo scored 65% in a test. She scored 26 marks. What was the test marked out of?
A tree was 15m tall in January. Now it is 18m tall. What is the percentage increase in height?
Another tree has grown 15% since January. It is now 46m high. What was its height in January?
Check out the Introduction to Ratio Grids if you are not already an expert!
When you are asked to do a currency conversion, you will usually be given an exchange rate first, as in this question:
“George changes some pounds into Euros. The exchange rate is £1=€1.18. If he changes £350 into Euros, how many Euros will he receive?”
Draw a simple Ratio Grid and give headings of £ and €. Put the numbers 1 and 1.18 in the correct columns. Then, the final number from the question, £350, goes in the £ column under the 1. Putting the numbers into their correct places is easy if you have headings! Put a ring around the empty space – that is where your answer will go.
In this grid, the 2 multiplying numbers are the “1.18” and the “350”, and you will divide by 1. So the sum will be 1.18×350÷1.
The answer is 413, and it is clearly in the Euros column, so give your answer as €413.
It’s easy if you get the headings right!
If you want lots of practice, Mr Corbett has a great set of currency conversion questions.
** Some of these questions are really challening – they may require 2 ratio grids, so think carefully! If an exchange rate changes, you will need a new grid for the new rate.
Ratio Grids can be used whenever you have a problem that starts with 3 numbers, and you have to times and divide. They are a clear way of laying out your working, and knowing which order to do the calculation.
You will need a calculator to do the practice questions, but first, here are 2 videos. The first shows you how to solve a small ratio grid, the second deals with the larger ones:
Your comments are very welcome – please use the box below.
Now you can use Ratio Grids to solve a Maths Problems, here are some types of problem you can try: