In order to estimate to nearest tens, we follow the following procedure :

Step I: Obtain the number.

Step II: Examine the digit at ones place.

Step III: If the digit at ones place is less than 5, then replace the ones digit by 0 and keep the other digits as they are;

If the digit at ones place is 5 or greater than 5, then increase tens digit by 1and replace the ones digit by 0.

The number so obtained is the number obtained by rounding off the given number to the nearest tens.



Let us consider some of the examples to estimate to nearest tens:

Round off each of the following numbers to the nearest tens:

(i) 87

Solution:

Ones or unit digit in 87 is 7, which is greater than 5.

So, we replace the ones digit by 0 and increase the tens digit by 1 to get the rounded off number.

Hence, rounded off number = 90.

(ii) 92

Solution:

The given number is 92.

Its ones or unit digit is 2, which is less than 5. So, we replace the ones digit by 0 to get the rounded off number.

Hence, rounded off number = 90.

(iii) 854

Solution:

The given number is 854.

Its ones or unit digit is 4, which is less than 5. So, we replace the ones digit by 0 to get the rounded off number.

Hence, rounded off number = 850.

(iv) 986

Solution:

The given number is 986.

Its ones or unit digit is 6, which is greater than 5. So, we replace the ones digit by 0 and increase the tens digit by 1 to get the rounded off number.

Hence, 986 is rounded off as 990 to the nearest tens.

(v) 999

Solution:

The given number is 999.

Its ones or unit digit is 9, which is greater than 5. So, we increase the tens digit by 1 and replace the ones digit by 0 to get the rounded off number.

Hence, rounded off number = 1000.

(vi) 9999

Solution:

The given number is 9999.

Its ones or unit digit is 9, which is greater than 5. So, we increase the tens digit by 1 and replace the ones digit by 0 to get the rounded off number.

Hence, rounded off number = 10000.

(vii) 10003

Solution:

The given number is 10003.

Its ones or unit digit is 3, which is less than 5. So, we replace the units digit by 0 to get the rounded off number.

Hence, rounded off number = 10000.

Estimate to nearest tens is the evident from the above examples that,

(i) The numbers having 1, 2, 3, 4 at ones or units place are rounded off downwards.

(ii) The numbers having 5, 6, 7, 8, 9 at ones or units place are rounded off upwards.

Important Note:
For estimating to the nearest 10, we look at the digit in the ones place. If it is 0, 1, 2, 3 or 4 we replace it by zero. If the digit in the ones place is 5, 6, 7, 8, or 9 we replace it by zero. If the digit in the ones place is 5, 6, 7, 8 or 9 we replace it by zero and increase the digit in the tens place by 1.