Page 23 - Start Up Mathematics_3

(b) 87 is rounded off to 90 since the digit at the ones place is 7 which
is more than 5.

(c) 65 is rounded off to 70 since the digit at the ones place is 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 place zeros at the tens and ones
place. The digit at the hundreds place remains the same.

• If the digit at the tens place is 5 or more, then place zeros at the tens and ones
place. Add 1 to the digit at the hundreds place.

Example 5: Round off (a) 243 and (b) 1887 to the nearest 100.

Solution: (a) 243 is rounded off to 200 because the digit at the tens place is 4.

(b) 1887 is rounded off to 1900 because the digit at the tens place is 8.

Rounding off to the nearest 1000

To round off a number to the nearest thousand, look at the digit at the hundreds place.
• If the digit at the hundreds place is 4 or less, then place zeros at the hundreds,

tens and ones place. Keep the digit at the thousands place as it is.
• If the digit at the hundreds place is 5 or more, then place zeros at the hundreds,

tens and ones place. Also, add 1 to the digit at the thousands place.
Example 6: Round off (a) 6253 and (b) 7923 to the nearest 1000.

Solution: (a) 6253 is rounded off to 6000 as the digit at the hundreds place is 2.
(b) 7923 is rounded off to 8000 as the digit at the hundreds place is 9.

Even and Odd Numbers

You have already studied that numbers which can be put in pairs are called even
numbers and numbers which cannot be put in pairs are called odd numbers.

For example, 238, 1746, 3280, 7632 are even numbers and 413, 685, 7981, 9377 are
odd numbers.

Number ending in
Number ending in
Numbers ending in Numbers ending in
0 2 4 6 8 1 3 5 7 9

ar
are odd numbers.
are even numbers. are even numbers.e even numbers.

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