Converting between FDP (CIE IGCSE Maths: Core)

How do I convert from a percentage to a decimal?

• Divide by 100 (move digits two places to the right)
• 6% as a decimal is 6 ÷ 100 = 0.06
• 40% as a decimal is 40 ÷ 100 = 0.4
• 350% as a decimal is 350 ÷ 100 = 3.5
• 0.2% as a decimal is 0.2 ÷ 100 = 0.002

 

How do I convert from a decimal to a percentage?

• Multiply by 100 (move digits two places to the left and add a % sign)
• 0.35 as a percentage is  0.35 × 100 = 35%
• 1.32 as a percentage is 1.32 × 100 = 132%
• 0.004 as a percentage is 0.004 × 100 = 0.4%

 

How do I convert from a decimal to a fraction?

• If it has one decimal place, write the digits over 10
• 0.3 is 
• 1.1 is 
• If it has two decimal places, write the digits over 100
• 0.07 is 
• 0.13 is  
• 30.01 is  
• If it has n decimal places, write the digits over 10ⁿ
• 0.513 is 
• 0.0007 is  
• Learn simple recurring decimals as fractions
• 0.33333… =   is   and 0.66666… =  is 
• Whole numbers can be written as fractions (by writing them over 1)
• 5 is 

 

How do I convert from a percentage to a fraction?

• Write the percentage over 100
• 37% is

 

How do I convert from a fraction to a decimal?

• Fractions written over powers of 10 are quicker
•  which is 0.6
•  which is 0.35
•  which is 0.002

 

How do I convert from a fraction to a percentage?

• Change fractions into decimals (see above), then multiply by 100
•  which is 0.8 as a decimal, which is 0.8 × 100 = 80%