Rounding Numbers to Decimal Places

Key Concepts

• Rounding numbers involves identifying the digit to be rounded (last digit) and the digit that will decide (decider).
• The decider determines whether the last digit remains the same or is rounded up.
  • Decider Values:
    • If 0, 1, 2, 3, or 4, the last digit stays the same (round down).
    • If 5, 6, 7, 8, or 9, the last digit is rounded up.

Examples

Example 1: Rounding to Two Decimal Places

• Number: 8.3175
• Goal: Round to two decimal places
• Last Digit: 1 (second place from decimal)
• Decider: 7 (third place from decimal)
• Since 7 is 5 or higher, round up 1 to 2.
• Result: 8.32

Example 2: Rounding to One Decimal Place

• Number: 217.631
• Goal: Round to one decimal place
• Last Digit: 6 (first place from decimal)
• Decider: 3 (second place from decimal)
• Since 3 is 4 or less, keep 6 the same.
• Result: 217.6

Example 3: Rounding to Three Decimal Places

• Number: 17.3695
• Goal: Round to three decimal places
• Last Digit: 9 (third place from decimal)
• Decider: 5 (fourth place from decimal)
• Since 5 is 5 or higher, round up 9 to 10.
  • This affects the digit in the column to the left, adding 1 to 6, making it 7.
• Result: 17.370
• Important to keep the zero in three decimal places.

Important Note

• Ensure the final result matches the requested number of decimal places to gain full marks in assessments.

Conclusion

• Rounding numbers depends on the position of the last digit and the decider.
• Always verify the final format to ensure compliance with the decimal place requirement.