To round to the first (or leading) digit, follow these rules:
Consider the digit after the leading one (that is, the second digit).
If it is less than 5 , leave the first digit unchanged and replace all other digits with zeros.
If the second digit is 5 or greater than 5 , add 1 to the leading digit and replace the rest of the digits with zeros.
E
Round each of the following numbers to the first (or leading) digit.
a 2371 b 872
THINK a Since the second digit (3) is less than 5, simply replace all digits except the first one with zeros.
WRITE a 2371
≈
2000 b The second digit (7) is greater than 5. So add 1 to the leading digit and replace the rest of the digits with zeros.
b 872
≈
900
Note that the sign
≈
is read as ‘is approximately equal to’.
Round each of the following numbers to the first (or leading) digit.
1 84
6 7235
2 77
7 5502
3 120
8 2970
4 569
9 23 004
5 903
10 59 455
 John Wiley & Sons Australia, Ltd 2001