Question

Round off to the nearest 10,100, and 1000:1289
A.$1290,1389,1009$\[\]
B. $1290,1300,1000$\[\]
C. $1280,1300,1200$\[\]
D. $1290,1200,1000$\[\]

Answer 1

Hint: We recall the rules of rounding off. We recall that we round off to nearest 10 by observing whether the one’ place is less than 5 or greater than equal to 5, we round off to nearest 100 by observing digit at the ten’s place is less than 5 or greater than equal to 5 , we round off to nearest 1000 by observing digit at the hundred’s place is less than 5 or greater than equal to 5 .

Complete answer:
We are given the number 1289. We see that it is a four digit number with 9 at the one’s place, 8 at the ten’s place, 2 at the hundred’s place and 1 at the thousand’s place. \[\]
Let us observe the digit at the one’s place to round off to nearest 10. The digit at one’s place is 9. We know that 9 is greater than 5, so we have to round up. We round by putting 0 instead of 9 and add 1 to the digit at the tens’ place that is $8+1=9$.We keep the digits 12 at rest of the places the same. Our rounded off number to nearest 10 is 1290. \[\]
Let us observe the digit at the ten’s place to round off to nearest 100. The digit at ten’s place is 8. We know that 8 is greater than 5, so we have to round up. We round by putting 0 instead of 8 and 9 and add 1 to the digit at the hundred’s place that is $2+1=3$.We keep the digit 1 at rest of a thousand. We have rounded off the number to nearest 100 as 1300.
Let us observe the digit at the hundred’s place to round off to the nearest 1000. The digit at hundreds places is 2. We know that 2 is less than 5, so we have to round down. We round by putting 0 instead of 2,8 9 and We keep the digit 1 at rest of the thousand's place unchanged. We have rounded off the number to nearest 1000 as 1000.

So the correct choice is B.

Note:
We should always remember that in rounding up means we add 1 to digit and rounding down we keep the digit unchanged. We use rounding to estimate the result where large numbers are being calculated. We must be careful that the rules of rounding for the digit 5 for whole numbers and decimals numbers are different. We see the next number after 5 is even or odd in decimal places.