Final answer:
To round a number to the nearest whole number, if the digit after the decimal point is 5 or greater, increase the whole number by 1. If the digit is less than 5, keep the whole number as is. This rule also applies to the significant figures in rounding after multiplication or division.
Step-by-step explanation:
To round a number to the nearest whole number, you should look at the digit to the right of the decimal point. If this digit is 5 or greater, you round up the last significant whole number by 1. If the digit is less than 5, you retain the last significant whole number and drop the digits after the decimal point. For example, to round 23.6 to the nearest whole number, you would round up to 24. But to round 23.4, you would simply round down to 23.
Significant Figures in Multiplication and Division
When rounding after multiplication or division, the result should be rounded to the number of significant figures in the least precise number used in the calculation. Use the same strategy when rounding off: if the digit to be dropped is less than 5, round down; if it's more than 5, round up.
Example of Rounding in Subtraction
Consider the subtraction 78,500 m - 362 m. The correct result after rounding would be 78,100 m because the first measurement's last significant digit is in the hundreds place, making it the most prudent point to round off to.