Page 21 - Start Up Mathematics_6

(d) In the number 46,785, the digit at tens place is 8. Since 8 > 5, we replace digits
at tens and ones place by 0 and add 1 to the digit at hundreds place. Therefore,
estimate of 46,785 to its nearest hundreds is 46,800.

Estimation or rounding off the numbers to the nearest thousands

Procedure:
Step 1: In the given number, examine the digit at hundreds place.

Step 2: If the digit at hundreds place is 0, 1, 2, 3, or 4, replace the digits at hundreds, tens and
ones place by 0 each and rest of the digits remain unchanged.
Step 3: If the digit at hundreds place is 5, 6, 7, 8 or 9, replace the digits at hundreds, tens and
ones place by 0 and add 1 to the digit at thousands place.

Example 21: Using the above mentioned procedure, estimate the following numbers to their
nearest thousands.
(a) 1,374 (b) 3,621 (c) 46,785

Solution: (a) In the number 1,374, the digit at hundreds place is 3. Since 3 < 5, we replace
digits at hundreds, tens and ones place by 0. Therefore, estimate of 1,374 to its
nearest thousands is 1,000.
(b) In the number 3,621, the digit at hundreds place is 6. Since 6 > 5, we replace
digits at hundreds, tens and ones place by 0 and add 1 to the digit at thousands
place. Therefore, estimate of 3,621 to its nearest thousands is 4,000.

(c) In the number 46,785, the digit at hundreds place is 7. Since 7 > 5, we replace the
digits at hundreds, tens and ones place by 0 and add 1 to the digit at thousands
place. Therefore, estimate of 46,785 to its nearest thousands is 47,000.

Representation of Whole Numbers on a Number Line

To represent whole numbers on a number line, follow these steps.
• Draw a straight line.

• Mark a point O on it.
• Label the point O as ‘0’.

• Now mark points on the right hand side of ‘0’ at equal distances as 1, 2, 3, 4, 5, ... and so on.

O
0 1 2 3 4 5 ...

The line shown above is a number line representing whole numbers. We observe that the number
on the left hand side is smaller than the number on the right hand side. For example, since 2 is on
the left of 5 on the number line therefore 2 < 5.

Rounding Off the Numbers Using Number Line

Let’s learn the concept of rounding off the numbers with the help of number line.
(i) Estimate 43 to its nearest tens.

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