Rounding Off Decimals -
1) Rounding Off To The Nearest Ones -
For rounding off the decimal fraction to the nearest ones, we see the digit in the tenths place. If it is less than 5 (i.e. 1, 2, 3, 4), the digit in the ones place remains the same, and the digit in the tenths place is replaced by 0. If the digit in the tenths place is 5 or more than 5 (i.e. 5, 6, 7, 8, 9), we add 1 to the digit in the ones place and replace the digit in the tenths place by zero.
Round off each of the following to the nearest ones:
a) 38.7
38.7 has 7 in the tenths place and 7 > 5, so in the answer 8 in the ones place becomes 8 + 1 = 9 and 7 in the tenths place is replaced by 0.
.: Answer is 39.0 = 39 (Ans.)
b) 642.3
642.3 has 3 in the tenths place and 3 < 5, so in the answer 2 in the ones place remains the same and 3 in the tenths place is replaced by 0.
.: Answer is 642.0 = 642 (Ans.)