Answer: Option B
:
B
To round off a number to the nearest ten, we checkthe last digitof the number.
If the lastdigitisless than 5, we round down the number to the nearest lower multiple of 10.
If the lastdigitis5or morethan 5, we round upthe number to the nearest highermultiple of 10.
In 20987, the digit in the ones place is 7. The nearest multiples of 10 for 20987 are 20980 or 20990.
Since7 is greater than5, 20987will be rounded off to 20990.