Question

what is the place value of the underlined digit? 3824
write the number in expanded form. 690
circle all the odd numbers. 7 14 54 33 90 45
find the sum. 8+1= 7+5= 9+8= 4+6= 2+9= 7+4= 6+7= 9+6=
round each number to the nearest 10. 97 ____ 44 __ 755 __ 273 __ 495 ____
round 439 to the nearest hundred.
round 681 to the nearest hundred.
use the place value strategy to find the sum. 357 + 164
use the place value strategy to find the difference. 427 - 243

Explanation:

1. Place - value of underlined digit in 3824

The underlined digit 2 is in the tens place. So its place - value is 20.

2. Expanded form of 690

The number 690 can be written as \(6\times100 + 9\times10+0\times1=600 + 90\).

3. Odd numbers

Odd numbers are not divisible evenly by 2. The odd numbers among 7, 14, 54, 33, 90, 45 are 7, 33, 45.

4. Sums

• \(8 + 1=9\)
• \(7+5 = 12\)
• \(9+8=17\)
• \(4 + 6=10\)
• \(2+9 = 11\)
• \(7+4=11\)
• \(6+7=13\)
• \(9+6=15\)

5. Rounding to nearest 10

• For 97, since 7>5, it rounds to 100.
• For 44, since 4<5, it rounds to 40.
• For 755, since 5 = 5, it rounds to 760.
• For 273, since 3<5, it rounds to 270.
• For 495, since 5 = 5, it rounds to 500.

6. Rounding to nearest 100

• For 439, since 39<50, it rounds to 400.
• For 681, since 81>50, it rounds to 700.

7. Sum using place - value strategy for 357+164

• Add the ones: \(7+4 = 11\), write 1 and carry 1.
• Add the tens: \(5+6 + 1(carry)=12\), write 2 and carry 1.
• Add the hundreds: \(3+1+1(carry)=5\). So \(357+164 = 521\).

8. Difference using place - value strategy for 427 - 243

• Subtract the ones: \(7-3=4\).
• Subtract the tens: Since 2<4, borrow 1 from the hundreds. So \(12 - 4=8\).
• Subtract the hundreds: \(3 - 2=1\). So \(427-243 = 184\).

Answer:

1. Place - value of 2 in 3824: 20
2. Expanded form of 690: \(600 + 90\)
3. Odd numbers: 7, 33, 45
4. Sums: \(8 + 1=9\), \(7+5 = 12\), \(9+8=17\), \(4 + 6=10\), \(2+9 = 11\), \(7+4=11\), \(6+7=13\), \(9+6=15\)
5. Rounding to nearest 10: 97→100, 44→40, 755→760, 273→270, 495→500
6. Rounding to nearest 100: 439→400, 681→700
7. Sum of 357+164: 521
8. Difference of 427 - 243: 184