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WELCOME TO MATH WITH MRS. CROSS
M6 A.3.1.1 and A.3.1.3
Practice place value while you wait:http://www.toonuniversity.com/flash.asp?err=496&engine=9
What we know…
http://www.youtube.com/embed/3uEafe1r4GI?rel=0 - Rounding Rap
Rounding RapYo, this is a story all about howMy math got twisted upside down,I’d like to take a minute so sit right hereI’ll tell you how I got from here to there.
First find the place, okay get itArrow to the right, underline the digit,5 or above, give it a shove-- 4 or less, stay at rest.
Flex your muscles like a heroDigits to the right turn to a zero,All the other digits remain the sameAnd that’s how its done in the rounding game!PEACE OUT!!
Estimation is ...
• Estimation is finding a number that is close enough to the right answer.
• You are not trying to get the exact right answer What you want is something that is good enough (usually in a hurry!)
When to use rounding…☺ When the question asks you to estimate.☺ When the question asks “about how many”…?☺ When an exact answer isn’t
possible.☺ When an answer is difficult to
obtain.
Rounding Numbers
• Numbers 1 – 4 = ROUND DOWN• Numbers 5 – 9 = ROUND UP
Rounding Numbers
• Numbers 1 – 4 = ROUND DOWN • Numbers 5 – 9 = ROUND UP
• Round 89• Round 14• Round 36
Place Value
9 1 2 , 4 3 6 , 7 8 2, 0 5 1h
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mil
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hu
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san
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tho
usa
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Watch me:Round to the nearest tens place:
First find the place, okay get it
4 7
Circle the number in the tens place.
Round to the nearest tens place:
Arrow to the right, underline the digit,
4 7Draw an arrow to the right of
the number. Underline.
Round to the nearest tens place:
5 or above, give it a shove-- 4 or less, stay at rest.
4 7
5 or above, give it a shove-- 4 or less, stay at rest.
4 7Add 1 to the tens place.
Round to the nearest tens place:
Flex your muscles like a heroDigits to the right turn to a zero,
All the other digits remain the sameAnd that’s how its done in the rounding game!
47 = _____
Round to the nearest tens place:
The Answer
47 rounded to the nearest tens
place is 50
40 5047
Note 47 is closer to 50 on the number line.
Round to the nearest thousands place:
First find the place, okay get it
3, 2 5 9Circle the number in the thousands place.
Round to the nearest tens place:
Arrow to the right, underline the digit,
3, 2 5 9Draw an arrow to the right of
the number. Underline.
Round to the nearest tens place:
5 or above, give it a shove-- 4 or less, stay at rest.
3, 2 5 9
2 shows us to do what?
5 or above, give it a shove-- 4 or less, stay at rest.
3, 2 5 92 should stay at rest
Round to the nearest tens place:
Flex your muscles like a heroDigits to the right turn to a zero,
All the other digits remain the sameAnd that’s how its done in the rounding game!
Round to the nearest tens place:
3,259 = _______
The Answer
3,259 rounded to the nearest
thousands place is 3,000
3,000 4,0003,259
Note 3,259 is closer to 3,000 on the number line.
Round these numbers to the nearest ten.
1) 256 =
2) 39 =
3) 7682 =
4) 956 =
5) 1231 =
6) 344 =
Round these numbers to the nearest hundreds.
1) 256 =
2) 3109 =
3) 76,982 =
4) 956 =
5) 1231 =
6) 344 =
Round these numbers to the nearest thousands.
1) 1256 =
2) 32,109 =
3) 76,982 =
4) 3956 =
5) 1231 =
6) 3474 =
Name the hundreds each is between
1. 516
2. 809
3. 447
4. 782
5. 124
6. 450
Name the tens each is between
1. 84
2. 33
3. 58
4. 91
5. 23
6. 15
Name the thousands each is between
1. 4,309
2. 6,500
3. 2,833
4. 5,432
5. 1,875
6. 3,598
Rounding to a Certain Place Value
• Estimate by rounding to the nearest ten. What numbers should you use to estimate 33 + 37?
• THINK:• Which is the nearest ten for 33?
• Which is the nearest ten for 37?
30 31 32 33 34 35 36 37 38 39 40
Estimate by rounding to the nearest ten. What numbers should use to estimate 56 + 67?
A. 50+60B. 50+70C. 60+60D. 60+70
• Round each number to the nearest ten and then add.
1,357 + 729
A. 2,000B. 1,700C. 2, 090D. 2, 100
Round each number to the nearest ten, and then solve.
48 + 57 = 32 – 12 = 45 + 15 =
68 – 22 = 93 + 33 = 88 – 54 =
Nearest Hundred
Nearest Hundred
• Round each number to the nearest hundred and then add.
274 + 3,964 =A. 3,400B. 4,100C. 4,300D. 4,000
• Estimate by rounding to the nearest hundred.What numbers should you use to estimate 641
plus 378?
A. 700 + 400B. 600 + 400C. 700 + 300 D. 600 + 300
Round each number to the nearest hundred, and then solve.
243 + 517 = 392 – 182 = 405 + 195 =
648 – 322 = 973 + 313 = 858 – 524 =
Which of the following should you use to estimate 5,789 – 4,678 to the nearest thousand?
A. 5,000 –5,000B. 6,000- 5,000C. 6,000-4,000D. 5,700-4,700
• Round each number to the nearest thousand and then subtract.
7,345 – 3,446
A. 4,000B. 3,000C. 5,000D. 2,000
Round each number to the nearest thousand, and then solve.
4,218 + 1,257 = 4,832 – 1,222 = 4,985 + 1,465 =
8,642 – 2,468 = 9,093 + 6,833 = 8,478 – 1,454 =
Estimation
• Remember Estimation is not an exact answer– It should be around the answer, but not exactly
it.• Round the numbers first, then calculate.
• Use Mental Math and Rounding to make numbers easier to work with.
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