Question

Do as directed.

Estimate the difference between $1890$and $1980$.

Answer 1

If the digit to the right of rounding place is $0,1,2,3,4$ ,we do not change the digit on rounding off place but change change all the digits to the right of it to zero and if the digit to the right of rounding off place is $5,6,7,8,9$ ,we add $1$to the digit on the rounding off place and change all the digits to to its right to zero.

$1980-1890=90$

So, estimate of difference between $1890$and $1980$ is $100$.

Hence, estimate of difference between $1890$and $1980$ is $100$.