Rounding Calculator: round numbers to decimals or integers

This rounding calculator rounds any number to the number of decimal places or significant figures you need, using standard rounding (half up) or banker's rounding.

Rounding rules

The most common methods are:

• Standard rounding (half up): if the next digit is 5 or greater, round up; if less than 5, round down.
• Banker's rounding: when the next digit is exactly 5, round to the nearest even digit to avoid cumulative bias.
• Truncation: simply drop the extra digits without rounding.

Standard rounding is the most widely used in everyday life and education.

Example 1: rounding to 2 decimal places

Problem: Round 3.14159 to 2 decimal places.

1. Identify the third decimal:
   • 3.14159, the third decimal is 1.
2. Since 1 < 5, round down:
   • 3.14.

Answer: 3.14159 rounded to 2 decimal places = 3.14.

Example 2: rounding to nearest integer

Problem: Round 7.85 to the nearest integer.

1. Identify the first decimal:
   • 7.85, the first decimal is 8.
2. Since 8 ≥ 5, round up:
   • 8.

Answer: 7.85 rounded to the nearest integer = 8.

Usos comuns

• Rounding monetary results to cents in finance.
• Adjusting significant figures in scientific and technical reports.
• Simplifying numbers for presentations and charts.
• Computing quick estimates for shopping and budgeting.
• Preparing data for systems that require fixed precision.
• Verifying rounding exercises in school homework.

Common mistakes when rounding

• Rounding in multiple steps (3.456 → 3.46 → 3.5) instead of directly.
• Confusing significant figures with decimal places.
• Not considering that rounding introduces a small error.
• Rounding intermediates in long calculations, accumulating errors.

Dica profissional

In multi-step calculations, never round intermediate values. Keep all decimals during the process and round only the final result to minimize accumulated error.