Estimate using front end estimation

Question

$2.32+$3.98+$0.74

Answer 1

In front end estimation of sum you add only the first digit of the numbers. The other digits are replaced by zeros.

 

$2.32 + $3.98 + $0.74

 

     ≈ $2.00 + $3.00 + $0.70

 

     ≈ $5.70

 

The exact answer is $7.04, so our estimate of $5.70 is a bit low,  Front end estimates will always be less than the actual sum because we round everything down.

Answer 2

With front end estimation, we only round and add the numbers in the leftmost place or the very last number on the left.

 if the numbers have two digits, round to the tens place before adding the leftmost digits or numbers

If the numbers have three digits, round to the nearest hundred place before adding the leftmost digits or numbers

If the numbers have four digits, round to the nearest thousand place before adding the leftmost digits or numbers

Using these rules, we get $2 + $4 +$1 = $7