Mental Math Grade 4 Day 32 | Mental Math - Free Printable

Let's solve the problems step by step:

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1. \( 25 \times 400 = \)

- Multiply \( 25 \) by \( 400 \):
\[
25 \times 400 = 25 \times (4 \times 100) = (25 \times 4) \times 100 = 100 \times 100 = 10,000
\]
- Answer: \( 10,000 \)

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2. \( 358 \div 7 = \) Quotient and Remainder

- Perform the division:
\[
358 \div 7 = 51 \text{ remainder } 1
\]
- \( 7 \times 51 = 357 \)
- \( 358 - 357 = 1 \)
- Quotient: \( 51 \)
- Remainder: \( 1 \)

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3. Write two fractions equivalent to \( \frac{4}{5} \)

- To find equivalent fractions, multiply both the numerator and denominator by the same number.
- Multiply by 2: \( \frac{4 \times 2}{5 \times 2} = \frac{8}{10} \)
- Multiply by 3: \( \frac{4 \times 3}{5 \times 3} = \frac{12}{15} \)
- Answer: \( \frac{8}{10} \) and \( \frac{12}{15} \)

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4. Who has the largest shoes in your class?

- This is a subjective question based on personal observation. You need to identify the person with the largest shoe size in your class.
- Answer: (Depends on the class)

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5. \( 20 \div 640 = \)

- Simplify the division:
\[
20 \div 640 = \frac{20}{640} = \frac{1}{32}
\]
- Answer: \( \frac{1}{32} \)

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6. Which of these numbers are divisible by 6? Circle them.

- A number is divisible by 6 if it is divisible by both 2 and 3.
- 353: Not divisible by 2 (odd number).
- 425: Not divisible by 2 (odd number).
- 624: Divisible by 2 (even number). Sum of digits: \( 6 + 2 + 4 = 12 \), which is divisible by 3.
- Answer: Circle \( 624 \)

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7. Five boys shared 210 marbles. How many did each receive?

- Divide the total marbles by the number of boys:
\[
210 \div 5 = 42
\]
- Answer: \( 42 \) marbles each

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8. Using commas, write eighty-eight thousand three hundred and two in numbers.

- Break down the number:
- Eighty-eight thousand: \( 88,000 \)
- Three hundred: \( 300 \)
- Two: \( 2 \)
- Combine them: \( 88,302 \)
- Answer: \( 88,302 \)

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9. Write the place value of 2 in 274,951.

- The digit \( 2 \) is in the hundred-thousands place.
- Answer: Hundred-thousands

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10. Without taking your pencil off the page, use only three straight lines to join these dots.

- Arrange the dots in a 3x3 grid:
```
• • •
• • •
• • •
```
- Solution: Draw a continuous line that connects all 9 dots using exactly 3 straight lines. This requires extending the lines beyond the boundaries of the grid.
- Answer: (Visual solution required)

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11. \( 11.5 \times (2 \times 9) = \)

- First, calculate \( 2 \times 9 \):
\[
2 \times 9 = 18
\]
- Then, multiply by \( 11.5 \):
\[
11.5 \times 18 = 207
\]
- Answer: \( 207 \)

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12. On what day does your birthday fall this year?

- This is a personal question. You need to provide the date of your birthday.
- Answer: (Depends on the individual)

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13. Find the difference between 1,441 and 4,888.

- Subtract the smaller number from the larger number:
\[
4,888 - 1,441 = 3,447
\]
- Answer: \( 3,447 \)

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14. Sunny’s cycle cost $800. Sunny paid one-fourth of the total amount. How much money did he pay?

- Calculate one-fourth of $800:
\[
\frac{1}{4} \times 800 = 200
\]
- Answer: $200

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15. A school bought 40 books, each with 60 pages. How many pages were there in all?

- Multiply the number of books by the number of pages per book:
\[
40 \times 60 = 2,400
\]
- Answer: \( 2,400 \) pages

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16. \( 9.28 \, \text{m} - 7.5 \, \text{m} = \)

- Subtract the two measurements:
\[
9.28 - 7.5 = 1.78
\]
- Answer: \( 1.78 \, \text{m} \)

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17. \( \_\_\_ \times 13 = 39 \)

- Solve for the missing number:
\[
x \times 13 = 39 \implies x = \frac{39}{13} = 3
\]
- Answer: \( 3 \)

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18. \( \frac{12}{19} - \frac{9}{19} = \)

- Subtract the fractions (same denominator):
\[
\frac{12}{19} - \frac{9}{19} = \frac{12 - 9}{19} = \frac{3}{19}
\]
- Answer: \( \frac{3}{19} \)

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19. 19.5 ten thousands = 5 × \_\_\_ = 50,000

- First, convert "19.5 ten thousands" to a number:
\[
19.5 \times 10,000 = 195,000
\]
- Now, solve for the missing number in \( 5 \times x = 50,000 \):
\[
x = \frac{50,000}{5} = 10,000
\]
- Answer: \( 10,000 \)

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20. Which weighs more: a kilogram of rocks or a kilogram of feathers?

- Both weigh the same because they are both specified as 1 kilogram.
- Answer: Same

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Final Answer Summary:

\[
\boxed{
\begin{array}{ll}
1. & 10,000 \\
2. & \text{Quotient: } 51, \text{ Remainder: } 1 \\
3. & \frac{8}{10}, \frac{12}{15} \\
4. & \text{(Depends on the class)} \\
5. & \frac{1}{32} \\
6. & 624 \\
7. & 42 \\
8. & 88,302 \\
9. & \text{Hundred-thousands} \\
10. & \text{(Visual solution required)} \\
11. & 207 \\
12. & \text{(Depends on the individual)} \\
13. & 3,447 \\
14. & \$200 \\
15. & 2,400 \\
16. & 1.78 \, \text{m} \\
17. & 3 \\
18. & \frac{3}{19} \\
19. & 10,000 \\
20. & \text{Same}
\end{array}
}
\]