Accuracy and Precision

Precision is the level of detail an instrument can measure

The smaller the unit, the more precise its measurement
For example, inch is more precise than foot as inch is a smaller unit than foot

As the length of the unit increases, the measurement becomes less precise

The more the digits after the decimal, the more precise the measurement

All non zero digits are significant

In a number without a decimal point, only zeros between non-zero digits are significant

Zeroes after the last non zero digit to the right of decimal point are significant

While adding or subtracting, the answer must have the same number of decimal places as the number (in the problem) with the least number of decimal places

Count the number of digits to the right of the decimal point for each number

Add or subtract the numbers

Identify the number (in the Problem) which has the least number of digits after decimal point. Count these digits (d)

Round the answer such that number of digits after the decimal point = d

While multiplying or dividing, the answer must have the same number of significant digits as the number (in the problem) with the least number of significant digits

Count the number of significant digits for each number

Multiply or divide the numbers

Identify the number (in the problem) which has the least number of Significant digits. Count these digits (d)

Round the answer such that number of Significant digits = d