Page 19 - ICSE Math 5

3. Write the smallest and the largest 7-digit numbers that can be formed using the digits 2,
8, 1, 3, 4, 5 and 7 without repeating any digit.
4. Write the following numbers.

(a) The largest 9-digit number having 3 different digits.

(b) The largest 7-digit number having 3 in the hundreds place.
(c) The predecessor and successor of 1 crore.

5. Arrange the following numbers in ascending and descending orders.
(a) 18,32,432; 13,22,431; 10,23,413; 12,34,341

(b) 10,40,000; 44,10,001; 9,14,004; 1,41,004

6. What number comes between the given numbers?

(a) 89,43,500 89,43,502

(b) 3,43,46,999 3,43,47,001

(c) 12,00,00,000 12,00,00,002

Rounding Off Numbers

We round off a number to get its approximate estimation. We round off numbers to the nearest
tens, hundreds, thousands and so on. Let’s revise the rules for rounding off numbers to the
nearest 10, 100 and 1,000.

Rounding Off to the Nearest 10

To round off a number to the nearest ten, look at the digit at the ones place.
• If the digit at the ones place is 4 or less, then write a zero at the ones place and let the digit
at the tens place remain as it is.

• If the digit at the ones place is 5 or more, then write a zero at the ones place and add 1 to
the digit at the tens place.
Example 10: Round off 69,33,89,427 to the nearest 10.
Solution: 69,33,89,427 is rounded off to 69,33,89,430 since the digit at the ones place is
7 which is more than 5.

Rounding Off to the Nearest 100

To round off a number to the nearest hundred, look at the digit at the tens place.
• If the digit at the tens place is 4 or less, then write zeros at the tens and ones places. The
digit at the hundreds place remains the same.
• If the digit at the tens place is 5 or more, then write zeros at the tens and ones places, and
add 1 to the digit at the hundreds place.

Example 11: Round off 64,34,76,586 to the nearest 100.
Solution: 64,34,76,586 is rounded off to 64,34,76,600 since the digit at the tens place is 8.

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