25-26 Barron's Class

Mystery Math #1

100

Convert 2,400 millimeters to meters 

(1 meter = 1,000 mm)

2.4 meters

200

Solve: 682 × 25 

17,050

300

A small cube measures 5 cm on one side.
What is the volume?

125 cm³

400

2¹/₃ × 4 =

9¹/₃ 

500

Find the error and solve again: 

7,245 ÷ 15

           40
  -----------
15 | 7245
    - 60
   ----------
      124
   -  120
   ---------
        45
      - 45
   --------
          0

Correct answer: 483
Error: Partial quotients were not combined correctly (40 is incomplete).

Mystery Math #2

100

Solve: 468 × 12 

5,616

200

Convert 750 grams to kilograms 

(1 kg = 1,000 grams)

0.75 kg

300

4,800 ÷ 10²

48

400

5.432 − 1.209

4.223

500

9,999 ÷ 25 =

399 R24

Mystery Math #3

100

Compare: 6.008 & 6.080

6.008 < 6.080

200

A box has a length of 6 cm, a width of 4 cm, and a height of 3 cm.
What is the volume?

72 cm³

300

Convert 5 feet to inches 

(1 foot = 12 inches)

60 inches

400

Solve these two problems & explain the difference in answers: 

A) 6 ÷ ¹/₂ 

B) ¹/₆ ÷ 2

A) 6 ÷ 1/2 = 12

B) 1/6 ÷ 2 = 1/12

Explanation: 

"If I start with a whole number, I end with a whole number" 

"If I start with a unit fraction, I end with a unit fraction"

500

A rectangular prism has a volume of 240 cubic centimeters.
Its length is 10 cm and width is 6 cm.
What is the height?

4 cm

Mystery Math #4

100

2.999 + 3.002

6.001

200

A small cube-shaped dice has volume. What unit would best measure it?

A. cubic millimeters (mm³)
B. cubic centimeters (cm³)
C. liters (L)
D. kilometers (km)

B. cubic centimeters (cm³)

300

6,384 ÷ 12 =

532

400

A bottle holds 1,250 mL. How many liters is that? 

(1 L = 1,000 mL)

1.25 L

500

Convert 16 cups to gallons 

(4 cups = 1 quart) 

(4 quarts = 1 gallon)

1 gallon

Mystery Math #5

100

Convert 2 hours to minutes 

(1 hr = 60 minutes)

120 minutes

200

Order from least to greatest: 

3.456, 3.654, 3.465, 3.546

3.456, 3.465, 3.546, 3.654

300

What does the 10³ represent & solve. 

0.89 × 10³ =

103 = 1,000

Correct Answer: 890

400

A shape has the following properties:

• It has 4 equal sides
• It has 4 right angles

Name all of the categories that it falls into: 

A. Quadrilateral
B. Rectangle
C. Square
D. Parallelogram
E. Rhombus
F. Triangle
G. Polygon

✔ A. Quadrilateral
✔ B. Rectangle
✔ C. Square
✔ D. Parallelogram
✔ E. Rhombus
✔ G. Polygon

❌ F. Triangle (incorrect — shape has 4 sides)

500

Find the error and solve again: 

   324

×   16

------

  1944

+ 324

------

  2268

Correct answer: 5,184
Error: The student did not correctly shift/place the tens product (×10). They treated 16 like 6 and 10 but misaligned the second partial product.