we know that
One very simple form of estimation is rounding.
To round off whole numbers:
Find the place value you want (the "rounding digit") and look to the digit just to the right of it.
If that digit is less than , do not change the "rounding digit" but change all digits to the right of the "rounding digit" to zero.
If that digit is greater than or equal to , add one to the rounding digit and change all digits to the right of the rounding digit to zero.
Part a) Estimate rounding the numbers to nearest hundreds
------> round up to
------> round down to
so
therefore
the answer part a) is
Part b) Estimate rounding the numbers to nearest tens
------> round up to
------> round down to
so
therefore
the answer part b) is