Number Ninjas
What is the value of the digit 7 in 47,382?
7,000 (seven thousand).
Round 8.476 to the nearest hundredth.
8.48.
What is 1/2 + 1/4? Write your answer in simplest form.
3/4.
How many centimeters are in 2.5 meters?
250 centimeters.
2.5 × 100 = 250.
A point is at (4, 7). What is its y-coordinate?
7.
What is 326 × 24?
7,824.
326 × 20 = 6,520; 326 × 4 = 1,304.
What is 14.8 + 6.37?
21.17.
What is 5/6 − 1/4? Write your answer in simplest form.
7/12.
10/12 − 3/12 = 7/12.
A rectangular prism is 8 cm long, 3 cm wide, and 4 cm high. What is its volume?
96 cubic centimeters.
8 × 3 × 4 = 96.
A pattern starts at 3 and adds 4 each time. What are the next three numbers?
7, 11, 15.
What is 3,648 ÷ 12?
304.
What is 4.6 × 3.2?
14.72.
What is 2 1/3 + 1 5/6?
4 1/6.
2 2/6 + 1 5/6 = 3 7/6 = 4 1/6.
A rectangular prism has a volume of 180 cubic inches. Its length is 9 inches and its width is 4 inches. What is its height?
5 inches.
180 ÷ (9 × 4) = 5.
Write a numerical expression for: Multiply the sum of 8 and 5 by 4.
(8 + 5) × 4.
Evaluate: 84 ÷ (9 − 2) + 6 × 3.
30.
84 ÷ 7 + 18 = 12 + 18 = 30.
A 12.6-meter ribbon is cut into pieces that are each 0.3 meter long. How many pieces are made?
42 pieces.
12.6 ÷ 0.3 = 42.
A recipe uses 3/4 cup of milk per batch. How much milk is needed for 2 1/2 batches?
1 7/8 cups.
3/4 × 5/2 = 15/8 = 1 7/8.
Two non-overlapping rectangular prisms form one solid. One measures 6 cm × 4 cm × 3 cm. The other measures 2 cm × 4 cm × 5 cm. What is the total volume?
112 cubic centimeters.
72 + 40 = 112.
A school buys 18 boxes of pencils with 24 pencils in each box. It gives out 275 pencils. How many pencils remain?
157 pencils.
18 × 24 = 432; 432 − 275 = 157.
6TH GRADE CHALLENGE: A teacher has 48 pencils and 72 erasers. She makes the greatest possible number of identical prize bags, using every item. How many bags can she make, and what goes in each bag?
24 bags, each with 2 pencils and 3 erasers.
The greatest common factor of 48 and 72 is 24.
6TH GRADE CHALLENGE: A backpack costs $48. It is on sale for 25% off. What is the sale price before tax?
$36.
25% of $48 is $12; $48 − $12 = $36.
6TH GRADE CHALLENGE: A baker has 4 1/2 cups of flour. Each batch of muffins needs 3/4 cup. If each batch makes 8 muffins, how many muffins can the baker make?
48 muffins.
4 1/2 ÷ 3/4 = 6 batches; 6 × 8 = 48.
6TH GRADE CHALLENGE: A triangular garden has a base of 12 feet and a perpendicular height of 7 feet. One bag of mulch covers 6 square feet. How many bags are needed to cover the garden?
7 bags.
Triangle area = (12 × 7) ÷ 2 = 42 square feet.
42 ÷ 6 = 7.
6TH GRADE CHALLENGE: At a camp, the ratio of counselors to campers is 2:15. There are 90 campers. How many counselors are needed to keep the same ratio?
12 counselors.
90 ÷ 15 = 6; 2 × 6 = 12.