Science Mathematical Skills I Rounding Rules Pro. Ignacio Anguera Colegio Real de Panamá The Perfect Partner for your Digital Business 4/27

ROUNDING NUMBERS RULES   ROUNDING NUMBERS RULES CASE 1 – Number Greater Than 5 If the number to the right of the least significant digit is GREATER THAN 5, round the least significant digit UP. Rounding means making a number simpler but keeping its value close to what it was. Example: 123456 rounded to five significant figures is 123460 Round the following numbers to 2 decimal places: 4.829 67.377 9.896 4/27

ROUNDING NUMBERS RULES   ROUNDING NUMBERS RULES CASE 2 – Number Lower Than 5 If the number to the right of the least significant digit is LESS THAN 5, keep the least significant digit SAME. Rounding means making a number simpler but keeping its value close to what it was. Example: 123456 rounded to three significant 123000. Round the following numbers to 2 decimal places: 4.822 67.370 9.894 4/27

ROUNDING NUMBERS RULES   ROUNDING NUMBERS RULES CASE 3 – 5 Alone If the number to the right of the least significant digit is EXACTLY 5 with no nonzero digits afterward, round the least significant digit UP if it is an ODD number; if it is EVEN, leave it unchanged. Rounding means making a number simpler but keeping its value close to what it was. Example: 12345 rounded to three significant 12340 Why does this rule exist? Because if the least significant digit is exactly 5, we should, on average, round the number up half the time, and down half the time; otherwise we risk an accumulation of round-off error in repeated calculations. Round the following numbers to 2 decimal places: 4.825 67.375 9.8950000000000 4/27

ROUNDING NUMBERS RULES   ROUNDING NUMBERS RULES CASE 4 – 5 And Something If the first figure dropped is EXACTLY 5, and there are any figures following the five that are not zero, then round the least significant digit UP Rounding means making a number simpler but keeping its value close to what it was. 124000 Example: 123501 rounded to three significant Round the following numbers to 2 decimal places: 4.8258 67.3752 9.89500000000003 4/27

ROUNDING NUMBERS RULES   ROUNDING NUMBERS RULES Rounding Rules If the first figure dropped is Rounding means making a number simpler but keeping its value close to what it was. Exactly 5 More Than 5 Less Than 5 digit UP digit SAME with no nonzero digits afterward with any nonzero digits afterward digit UP Even Odd digit SAME digit UP 4/27

# of decimal places desired First figure to be dropped ROUNDING NUMBERS RULES   PRACTICE! NUMBER # of decimal places desired Last figure to be kept First figure to be dropped Rule Number becomes 6.422 1 6.4 6.42 6.4872 2 6.997 6.6500 7.485 6.755000 8.995 6.6501 7.4852007 4/27