Rounding to a Given Place Value (Cambridge (CIE) IGCSE Maths)

Rounding to a Given Place Value

How do I round a number to a given place value?

• Identify the digit in the required place value

• Identify the two options that the number could round to

  • Count in the units you are rounding to,

  • Find the first value below and the next value above the number you are rounding 

    • E.g. Round 1294 to the nearest 100, count in 100's

    • The number will round down to 1200 or up to 1300

  • Be careful if your digit is a 9 and the next number up will affect the higher place values

    • E.g. Rounding 1798 to the nearest 10, count in 10's

    • The number will round down to 1790 or up to 1800

• Circle the number to the right of the required place value

  • If the circled number is 5 or more then you round to the bigger number

  • If the circled number is less than 5 then you round to the smaller number

  • Put a zero in any following place values before the decimal point

    • E.g. 1567.45 to the nearest 100 would be 1600

How do I round a number to a given decimal place?

• Identify the position of the decimal place you are rounding to

• Identify the two options that the number could round to

  • E.g. Round 7.82741 to 3 d.p., count in 0.001's

  • The number will round down to 7.827 or up to 7.828

• Circle the number to the right of the required decimal place

  • If the circled number is 5 or more then you round to the bigger number

  • If the circled number is less than 5 then you round to the smaller number

    • E.g. 2.435123 to the nearest 2 d.p. would be 2.44

• When rounding to decimal places make sure you leave your answer with the required amount of decimal places

  • Do not put any zeros after the position of the decimal place you are rounding to

    • E.g. 1267 to the nearest 100 is 1300

    • But 1.267 to two decimal places (nearest 100th) is 1.27 not 1.270

  • If asked for a certain number of decimal places, you must give an answer with that number of decimal places

    • E.g. 2.395 to two decimal places is 2.40 (do not write 2.4)