Estimating sums and differences

Division: (up to 4 digit number by single digit number)

Estimating sums and differences:

To estimate a number means to round of each number to its nearest tens, hundreds and then add or subtract.

Steps for estimation:

Nearest to tens: check the unit digit of the given number that is to be estimated.

i) if it is equal to (or) greater than 5, add 1 to previous digit, make the unit digit as zero. (e.g.) 85 is rounded to 90

ii) if it is less than 5, make the unit digit as zero. (e.g.) 63 is rounded to 60

Note: We can estimate a number nearest 1000 and more.

EXAMPLE 1

1) Estimate the sum.

2) Estimate the difference