Date post: | 12-Jul-2015 |
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• number notation and place values (ten thousands, thousands, hundreds, tens, ones)
• rounding off numbers to the nearest
10 or 100
• use of the approximation
symbol (≈)
What will we learn today?
Whole Numbers Numbers up to 100 000
So, in a 5-digit number,
There are
Ten thousands place
Thousands place
Hundreds place
Tens place
Ones place
In 9265, the digit 2 is in the ___ place.
a) ones
b) tens
c) hundreds
d) thousands
The ‘2’ stands for 200.
rounding off numbers to the nearest 10 or 100, and learn the use of the approximation symbol (≈)
Let’s try:
Rounding off Numbers
Look at the digit to the right of the required place value.
– If the digit is less than 5,
round down.
– If the digit is 5 or more,
round up.
Solution
1) Round off 483 to the nearest hundred. Answer:500 (8 is more than 5 so we round up)
To round off a number correct to a given place, we round up (that is add 1) if the next figure is 5 or more, we round down (that is just drop them) if the next number is less than 5.
Try this out!
Round off 314 to the nearest hundred.
3 | 14 ≈ 300
1 is less than 5, so we just drop 14. That is why we round down to 300.
What is the best estimate for 589 x 61 ?
(1) 500 x 60
(2) 500 x 70
(3) 600 x 60
(4) 600 x 70
589 ≈ 600
Let’s try rounding off the number.
What is the best estimate for 589 x 61 ?
(1) 500 x 60
(2) 500 x 70
(3) 600 x 60
(4) 600 x 70
61 ≈ 60
Let’s try rounding off the number.
What is the best estimate for 589 x 61 ?
(1) 500 x 60
(2) 500 x 70
(3) 600 x 60
(4) 600 x 70
Compare your answers with the given option
589 ≈ 600
61 ≈ 60
What is the best estimate for 589 x 61 ?
(1) 500 x 60
(2) 500 x 70
(3) 600 x 60
(4) 600 x 70
Compare your answers with the given option
589 ≈ 600
61 ≈ 60