Math practice for 13 year olds - page 318 of 413
Number of problems found: 8260
- Two numbers
The sum of two numbers is 10,000, and one is four times larger than the other. What are two numbers? - Break percentage
Students have classes from 8:00 to 12:30. One 15-minute break and three 10-minute breaks between lessons. What percentage of teaching is breaking? - Percents
How many percents is 900 greater than the number 750? - Above 100%
Find 340 percent of the numbers 45 and 55. - Atomic diameter
The diameter of the atomic nucleus is 10 to -12 cm. How many atoms would fit on a 1 mm line if they could be arranged close together? - Cylinder height
The rotating cylinder has a diameter of 14 cm and a surface of 1,186.92 cm². Calculate the height of the cylinder. - Percents of percentages
Calculate: (a) 5% of 25% of 85 b) 4% of 20% of 1500 c) 83% of 20% of 25 d) 0.3% of 70% of 90 - Number increase Increase number 160 by: a) 25% b) 30% c) 150%
- Square root sum
Determine the sum of the square roots of the number 25. - Average temperature
The following temperatures were measured every 6 hours from 6 to 24 hours: -2.2 C, 2.1 C, 5.4 C, 3.9 C, 0.7 C, -1.9 C, -3.8 C. Calculate the average temperature from 6 to 24 hours. - Area of a cube
Calculate the surface area of a cube if its volume is equal to 729 cubic meters. - Ball count
Roland has 490 balls. If he gave 145 bullets to Mark, he would still have 100 more bullets than Mark. How many balls did Mark have at the beginning? How many shots do they have together? - Dimensions of glass
An aquarium has dimensions of 64 × 50 × 45 cm and is filled to 5 cm below the upper edge. How many liters of water are in an aquarium? How many square meters of glass are needed to produce an aquarium? - Glass
How many glasses are needed to produce glass with a base of a regular 5-gon if one base triangle in the base is 4.2 square cm and the height is 10 cm? - Z9-I-4
Kate thought of a five-digit integer. She wrote the sum of this number and its half in the first line of the workbook. Write a total of this number and its fifth on the second line. She wrote a sum of this number and its one ninth on the third row. Finall - Tunnels
Mice built an underground house consisting of chambers and tunnels: • every tunnel connects one chamber to another (no dead ends), • exactly three tunnels lead from each chamber to three distinct other chambers, • from every chamber, a mouse can reach any - Unknown number
16% of the unknown number equals the square root of the number 25. Find this unknown number. - Square diagonal
Determine the diagonal of a square whose perimeter is equal to 72 cm. - Average speed
At what average speed would you have to travel around the world in 80 days? (Assume a path along the equator; round to km/h.) - Area and percents
Find what percentage is a smaller cube surface when the wall's surface area decreases by 25%.
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