Math Lesson 1
Numbers up to the Millions
Read and Write Whole Numbers in the Millions | Order and Compare Whole Numbers and Decimals | Order of Operations Using a Scientific Calculator | Order of Operations: the Manual Approach | Round off Whole Numbers
|ROUND OFF WHOLE NUMBERS|
|CA GR4 NS 1.3 & 1.4|
|Sometimes it is easier to use rounded off numbers. For example it
is easier to say about 100 than 98.9. Rounded numbers end with
one or more zeroes.
Ask "is 48 closer to 40 or 50?" It is closer to 50, it is about 50.
Ask "if 81 is closer to 80 or 90?" It is closer to 80. It is about 80.
Round off the same way for larger numbers.
Is 43,556 closer to 40,000, or 50,000? Compare the first two numbers. 43 is closer to 40 than 50. It is 40,000.
"Tricky" numbers are those with 5 as the number that decides. Is 650 closer to 600 or 700? On a number line 650 is half way. Math has a rule for this. When the digit is 5 or greater, round up. When the digit is less than 5, round down.
You may need to estimate to a certain place. Look at the number in the place to the right. Then round. Round 684 to the tens place.
A 4 is right of the tens in the ones place. It rounds to 680.
6423 rounded to the nearest 10 is 6420.
For another set of examples use 589,457:
Rounded to the nearest 10, it is 589,460.
The named estimate place will have the same number of zeros as the number you round to.
Worksheet 1 Rounding to the nearest 10
Worksheet 2 Rounding to the nearest 100
Worksheet 3 Rounding to the nearest 1,000
Worksheet 5 Rounding to the nearest million and ten million