Question

Give a rough estimate (by rounding off to nearest hundreds) and also a closer estimate (by rounding off to nearest tens) :$439+334+4,317$

Answer 1

Step 1 : Rough estimate of $439+334+4,317$by rounding off to nearest hundreds:

For rounding off to nearest hundreds,we first check the digit at ten's place.If the digit at ten's place is less than $5$ then we replace its ten's and one's place by zero but if the digit at ten's place is $\ge 5$ then we add $1$ to hundred's place digit and then replace ten's place and one's place by zero.

$$\begin{gathered} 439\to 400 \\ 334\to 300 \\ 4317\to 4300 \\ So,439+334+4317\to 400+300+4300 \\ =5000 \end{gathered}$$

Step 2 : Closer estimate of $439+334+4,317$by rounding off to nearest tens:

For rounding off to nearest tens,we first check the digit at one's place.If the digit at one's place is less than $5$ then we replace it by zero but the digit at one's place is $\ge 5$ then we add $1$ to ten's place digit and replace one's place by zero.

$$\begin{gathered} 439\to 440 \\ 334\to 330 \\ 4317\to 4320 \\ So,439+334+4317\to 440+330+4320 \\ =5090 \end{gathered}$$

Hence,Rough estimate of $439+334+4,317$by rounding off to nearest hundreds is $5000$ and Closer estimate of $439+334+4,317$by rounding off to nearest tens is $5090$.